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ECONOMIC AND SECTOR WORK

CARBON SEQUESTRATION
IN AGRICULTURAL SOILS

M AY 2 0 1 2

REPORT NUMBER: 67395-GLB

ECONOMIC AND SECTOR WORK

CARBON SEQUESTRATION
IN AGRICULTURAL SOILS

REPORT NO. 67395-GLB

ARD

AGRICULTURE AND
RURAL DEVELOPMENT

© 2012 International Bank for Reconstruction and Development/International Development Association or
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Cover Photos: Scott Wallace, Tran Thi Hoa, Curt Carnemark, Ami Vitale, and Ray Witlin.

CONTENTS

TABLE OF CONTENTS

List of Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v
List of Photos . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi
List of Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii
List of Boxes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . viii
Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi
Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii
Executive Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv
Chapter 1: Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1: Food Security Under a Changing Climate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2: Carbon Benefits Through Climate-Smart Agriculture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.3: Objectives and Scope of the Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Chapter 2: Soil Organic Carbon Dynamics and Assessment Methods . . . . . . . . . . . . . . . . . . 5
2.1: Soil Organic Carbon Dynamics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.2: Carbon Assessment for Land Management Projects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2.3: Techniques of Soil Carbon Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2.4: Carbon Assessment in The World Bank’s Sustainable Land Management Portfolio . . . . . . . . . . . . . 17

Chapter 3: Meta-Analyses of Soil Carbon Sequestration . . . . . . . . . . . . . . . . . . . . . . . . . . 19
3.1: Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
3.2: Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
3.3: Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Chapter 4: Ecosystem Simulation Modeling of Soil Carbon Sequestration . . . . . . . . . . . . . . 43
4.1: Model Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
4.2: Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Chapter 5: Economics of Soil Carbon Sequestration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
5.1: Marginal Abatement Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
5.2: Trade-Offs in Soil Carbon Sequestration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
5.3: Implications of the Trade-Offs in Land-Use Decisions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
5.4: Sustainable Land Management Adoption Barriers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
5.5: Policy Options for Soil Carbon Sequestration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

EC O N O M I C A N D S E CT OR WORK

III

IV

C ONTENTS

Appendix A: The Farming Practice Effect, Number of Estimates, and Features in Land
Management Practices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Appendix B: General Scenario Assumptions and Application for World Regions . . . . . . . . . . 67
B.1: Baseline Scenario . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
B.2: Global Mitigation Scenarios . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
B.3: Application to World Regions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
B.4: Detailed Modeling for Africa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

Appendix C: Global Crop Yields (T ha −1 yr−1) Grouped into 25th, 50th, and 75th Percentile
Bins Corresponding to Low, Medium, and High . . . . . . . . . . . . . . . . . . . . . . . 75
Appendix D: Uncertainty Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
Appendix E: Assumptions for Deriving the Applicable Mitigation Area for the Land
Management Practices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
E.1: Africa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

CARBON SEQUESTRATION IN AGRICULTURAL SOILS

LI S T O F F I G U R E S

LIST OF FIGURES

Figure E1: Abatement Rates of the Land Management Practices (t CO2e Per Hectare Per Year) . . . . . . . . . .xxii
Figure E2: Trade-Offs Between Profitability and Carbon Sequestration of Sustainable Land Management
Technologies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xxv
Figure E3: Relationship Between Private Benefits and Public Costs . . . . . . . . . . . . . . . . . . . . . . . xxvi
Figure 1.1: Contribution of Different Sectors to Greenhouse Gas (GHG) Emissions . . . . . . . . . . . . . . . . . 1
Figure 1.2: Proportion of Agricultural Land Derived from Different Land Covers in the Tropics, 1980–2000 . . . . . 2
Figure 2.1: Carbon Stocks in Biomass and Soils. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Figure 2.2: Global Soil Regions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Figure 2.3: Factors Affecting Soil Carbon Sequestration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Figure 3.1: Geographical Distribution of Carbon Sequestration Estimates . . . . . . . . . . . . . . . . . . . . . 21
Figure 3.2: Soil Carbon Sequestration and Precipitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Figure 3.3: Soil Carbon Sequestration and Temperature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Figure 3.4: Soil Carbon Sequestration and Soil Order . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Figure 3.5: Soil Carbon Sequestration and Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Figure 3.6: Soil Carbon Sequestration and Application Levels of Nitrogen Fertilizer
(Means and 95 Percent Confidence Intervals, n = 285) . . . . . . . . . . . . . . . . . . . . . . . . . 26
Figure 3.7: Soil Carbon Sequestration and Fertilizer Combinations (Means and 95 Percent Confidence
Intervals, n = 285) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Figure 3.8: Mean Soil Carbon Sequestration and Levels of Residue Returned . . . . . . . . . . . . . . . . . . . 30
Figure 3.9: Classification of Tillage Systems Based on Crop Residue Management . . . . . . . . . . . . . . . . 31
Figure 3.10: Mean Soil Carbon Sequestration and Cropping Intensity . . . . . . . . . . . . . . . . . . . . . . . 33
Figure 3.11: Carbon Dioxide Abatement Rates of the Land Management Practices . . . . . . . . . . . . . . . . 39
Figure 4.1: Representation of the RothC Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Figure 4.2: The 12 Strata Used for Ecosystem Simulation Modeling . . . . . . . . . . . . . . . . . . . . . . . . 45
Figure 4.3: Africa Agroecological Zone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Figure 4.4: A Screen Shot of the Soil Carbon Internet Database . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Figure 4.5: Cumulative Soil Carbon Loss by 2030 Assuming 15 Percent Residue Retention (t ha−1)
under Different Cropping Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
EC O N O M I C A N D S E CT OR WORK

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. . . .VI LIST O F FIGUR ES Figure 4. . . . . . . . . . . . . . . . . . . . . xxiv Photo E. 34 Photo 3. . . . . . . . . . 29 Photo 3. .xxv Photo 3. . . . . . . . . . . . . . . . . . . . . .1: The Private Marginal Abatement Cost Curves. . . .2: Water Management in a Field in India . . . . . . . . . . . . . .2: Crop Residue Management in Irrigated Fields in Indonesia . . . . . . . . . . . . . . . . . .xvii Photo E. . .1: Crop Residue Management in Irrigated Fields in Indonesia . .1: Terracing and Landscape Management in Bhutan . . . 56 Figure B. . . .1: FAO Land-Use Map . . . . . . . . . . . . . . . . . .4: Relationship Between Private Benefits and Public Costs in Africa . . . .2: Total Private Benefits (Blue) and Public Costs (Red) of Land Management Practices (US$.4: Crop Harvesting in Mali. . . . . . . .6: Predicted Cumulative C Sequestration for Different Land Management Practices by 2030 . . . . . . . . . . . . . . . . . . . .3: Water Management in a Field in India . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5: Crop Harvesting in Mali. . . . . . . . . . . . . . . . . . . . . . . . . . 71 LIST OF PHOTOS Photo E. . . . . . . . . . . . . . 55 Figure 5. . . . . .4: Maize Growing under Faidherbia Albida Trees in Tanzania . . . . . . . . . . . . . . . . . . . . . . . . . 49 Figure 5. . . . . . . . . . . . . . . . . 57 CARBON SEQUESTRATION IN AGRICULTURAL SOILS . . . . . . . . . . xx Photo E. . . . . . . The Biomass Is Smaller Compared to that of Agroforestry Systems. . . . . . . . . . . . . . 33 Photo 3. . . . . . . . .3: Maize Growing under Faidherbia Albida Trees in Tanzania . . . . . . . . . . . . . . . . . . . . . . . . . . . .3: Trade-Offs Between Profitability and Carbon Sequestration of Sustainable Land Management Technologies in Africa . . Billion) for the B1 Scenario . . . . . . . . . . . . . . . . . . 52 Figure 5. . . . . . . . . 54 Figure 5. . . . . . . The Biomass Is Smaller Compared to that of Agroforestry Systems. . . . . . . . . . . . . . .1: Terracing and Landscape Management in Bhutan . . . . . . . . . . . . 40 Photo 5. . . xxiii Photo E. . . .

14 Table 2.5: Estimate of Erosion-Induced Carbon Emission . . . . . . . . . . . 3 Table 1. .6: Water Management and Soil Carbon Sequestration Rates (kg C ha−1 yr−1) . . . . . . . 28 Table 3. . . . . . . . . . . . . . . . . . .9: Comparative Features of Some Carbon Estimation Models . . . . . and Soil Carbon Sequestration Rates (kg C ha−1 yr−1) . . . . . . . . . . . .2: Estimated Increase in Grain Crop Production From Land Management Technologies That Sequester Soil Carbon (Million Tons Per Year) . . . . . 8 Table 2. . Grassland. . . . .3: Relative Importance of the Four Domains of Integration on Crop-Livestock Interaction . . . . . . . . . . . . . . . . . . . . xviii Table E3: Technical Mitigation Potential. .11: Carbon Accounting Systems and Tools . . . . . . . 10 Table 2. . . . . . . . . . . . . . . . . 36 EC O N O M I C A N D S E CT OR WORK V II . . . . . . 32 Table 3. . . . . . . . . . . . . . . . . . . . . . . 15 Table 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Table 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8: Land-Use Changes and Soil Carbon Sequestration Rates (kg C ha−1 yr−1). . . . . . . . . . . . . . . . 19 Table 3. . . . . . . . . . . . . 14 Table 2.1: Practices That Sequester Carbon in Forest. . . . . . . . . . . . . . . and Cropland . . . . . 7 Table 2.xvii Table E2: Estimates of Erosion-Induced Carbon Emission Across World Regions. . . . . . . . . . . . . . .2: Global Carbon Budget (Gt C) . . . . .LI S T O F TA B L E S LIST OF TABLES Table E1: Carbon Stocks in Vegetation and Top 1 Meter of Soils of World Biomes . . and Public Costs of the Land Management Technologies by 2030 . . . . . . . . . . . . . . .5: Crop Rotation and Soil Sequestration Rates (kg C ha−1 yr−1) . . . . . 29 Table 3. xxvii Table E4: Relative Importance of Different Factors for Adopting Improved Land Management Practices . . Crop Residue Management. . . . . . . . . . .7: Agroforestry and Soil Carbon Sequestration Rates (kg C ha−1 yr−1) . . . . . . . . . . . 13 Table 2. . . . . . 6 Table 2. . . . . . . . . . . . . . . 6 Table 2. . . . 16 Table 3. . . 27 Table 3. . . . . . . . . . . . . . . . . . . . 16 Table 2. . . . . . . . . . .3: Forms of Carbon in the Soil . . . . . . . . . .1: Improvement in Crop Yields Per Ton of Carbon in the Root Zone . . . . . . . . . . . . . . . . .4: Tillage. . . . . . . . . . . . . . . . . . . . . . . .8: Characteristics of Emerging In Situ Methods of Soil Carbon Analytical Techniques . . . . . . .6: Comparison of Carbon Assessment for Carbon Mitigation and Noncarbon Mitigation Projects . . . . . .2: Nutrient Management and Soil Carbon Sequestration Rates (kg C ha−1 yr−1) . . . . . . . . . . . . . . . . .1: Carbon Stocks in Vegetation and Top 1 Meter of Soils of World Biomes . . . . . . . . . . . . . . . . . xxviii Table 1. . . . .4: Soil Carbon Pool up to 1-Meter Deep for Soil Orders of the World’s Ice-Free Land Surface . . . . . . . . .10: Components of Soil Carbon Monitoring at the Regional Scale . 35 Table 3. .7: Direct and Indirect Methods of Soil Carbon Assessment. . . . . . . . . . . . . . . . . . 34 Table 3. . . . . . . . . . . . . . . . . . . . . . . . . Private Benefits. . .

. . . . . 55 Table 5. . . . . . . . . . . . 84 LIST OF BOXES Box 2. . . . . . . . . . . . . . . . . .5: Interventions for Facilitating Increased Input Use . . . . . . . . . 82 Table E. . . . . . . . . . . . .3: Technical Mitigation Potential. . . . .1: Brief Description of Soil Orders . . . . . . . . . . . .2: Sustainable Land Management Practices Reverse Soil Carbon Loss in Java. . . . . . . . .2: Public Costs of Different Technologies Per Ton of Carbon Dioxide Sequestered. . . . . . . . . . . .5: C Inputs for Different Agroforestry Systems . . . . . .3: Manure C Inputs for the AEZs in Africa Based on FAOSTAT . . . . . . . . . .1: Agricultural Systems and Mitigation Scenario in South America . . . . . . . . . . . . . . 53 Table 5. 50 Table 5. . . . . . . . . .1: Spatial Datasets Used in the Study . . . . . . . . . . . . . . . 44 Table 4. . . . . . . . . . . . and Public Costs of the Land Management Technologies by 2030 . . .VIII LIS T OF TA B LES Table 3. . . . . . . . . . . . . . . . . . . 69 Table B. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4: Relative Importance of Different Factors for Adopting Improved Land Management Practices . . . . . . . 72 Table B. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1: Risk-Related Barriers to Adoption of Soil Carbon Sequestration Activities . . . . . .1: Uncertainty Analyses Using Random Samples from the Mitigation Scenarios. . . 83 Table E. . . . . . . . . . . . . . Private Benefits.2: Modeled Cumulative Soil Carbon Sequestration Potential by 2030 (Mt C) under Different Land Management Practices . . . . . . . . . 70 Table B. . . . . . . . . . . 73 Table D. . . . . . .2: Agricultural Systems and Mitigation Scenario in Central America . . . . . . . 53 Table 5. .4: C Inputs for Different Green Manure/Cover Crop Systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 Table B. . . . . .10: Soil Amendments and Soil Carbon Sequestration Rates (kg C ha−1 yr−1) . . . . . . . 37 Table 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Box 5.1: Estimated Cropland Area in the 2000s . . . . . 60 Table 5. . .1: Private Savings of Different Technologies Per Ton of Carbon Dioxide Sequestered . . . . . . .9: Summary of Observed Rates of Soil Carbon Sequestration (kg C ha−1 yr−1) as a Result of Land-Use Changes and Other Practices Relevant to Livestock Management . . . . . . 69 Table B. . . . . . . 59 CARBON SEQUESTRATION IN AGRICULTURAL SOILS . . . . . . . . . 38 Table 4. . . . . . . . . . . . 9 Box 2. . . . . . . . . . . . . .2: Estimated Cropland and Grassland Area by 2030 (Million Hectare).

It also grew out of the recognition that conventional forms of agricultural production are often unsustainable and deplete or “mine” the natural resources on which production relies over time. and increases the resilience of farmland. reducing both the need for fertilizer applications and susceptibility to land degradation. and for the food security of vulnerable populations in particular. Yet the same carbon that is sequestered through sustainable practices makes those practices more productive. they can be highly productive and profitable. More recently. Perhaps the most important point conveyed in this document is that the dual roles of agriculture as a source of food security and as a source of environmental services converge in fundamental ways. this new and more sustainable pattern of agricultural development can make the sector an active agent in climate change mitigation at the same time that it improves and builds upon the sector’s capacity to adapt to the increasing temperatures and declining precipitation that are already reducing yields of grains and other primary crops in many parts of the vast semi-arid tropics where so many of the poorest reside. And it also relies on the climate at the same time that its role in the global carbon cycle makes it a major contributing factor to climate change. but it is not its only priority. Agriculture employs up to two-thirds of their workforce and accounts for between 10 and 30 percent of their gross domestic product. a substantial source of carbon emissions. Higher carbon content enables the soil to make more water and nutrients available to support crop growth. Too often the relationship between these roles is viewed as a series of painful trade-offs. Today. and a variety of biological processes. While agriculture emits a large volume of greenhouse gases. we understand not only the significance that climate has for agriculture. its biomass and especially its soils also sequester carbon out of the atmosphere. water. Production relies directly on soil. EC O N O M I C A N D S E CT OR WORK IX . fiber and fuel. Food production will need to effectively double in many developing countries by 2050 to feed a growing and increasingly urban global population. and in addition to their technical feasibility. The growing consensus on the need for a climate-smart agriculture emerged largely out of international awareness of the sector’s negative impacts—its ecological footprint. Some 30 percent of global greenhouse gas emissions are attributable to agriculture and deforestation driven by the expansion of crop and livestock production for food. Agricultural production operates under intensifying pressures. and that leads to higher profit margins for producers. These technical elements of climate-smart agriculture are by now well understood. and the principal driver behind deforestation worldwide. Agriculture is the world’s leading source of methane and nitrous oxide emissions. and this role as a carbon sink and as a carbon store can be strategically optimized through proven farming techniques and methods that simultaneously reduce emissions. with a growing understanding of the environmental services the sector can provide if production is well-managed.PR E FA C E PREFACE Agriculture’s direct reliance on the natural resource base has always been a defining characteristic of the sector. As this document will discuss. Increasing productivity is agriculture’s most pressing priority. The agriculture systems that supply this food play a pivotal role in these countries’ economies. This trend is projected to intensify in the coming decades and have serious ramifications for global food security. but also the enormous significance that agriculture has for the climate. this perspective of agriculture as a source of greenhouse gas emissions and pollution has become more balanced. The carbon that is removed from the atmosphere and captured in soils and plant biomass is the same carbon that makes agricultural soils more fertile. more than ever before. The Intercontinental Panel on Climate Change (IPCC) indicates that carbon sequestration accounts for about 90 percent of global agricultural mitigation potential by 2030.

Among the most important of these constraints are the significant upfront expenditures that many of the newer techniques require.X PR EFA C E While technical progress in the area of integrated “landscape” approaches to managing natural and economic resources has been very promising. Mobilizing and targeting resources to overcome these constraints has been an important reason the World Bank became determined to get climate-smart agriculture more firmly onto the agenda of the international dialogue on climate change. In many of the developing countries in which these techniques would wield some of their most important benefits. the adoption of these approaches still faces serious constraints in many developing countries. improved climate resilience. and enhanced mitigation an integral part of that dialogue. In some settings there is limited capacity to implement them even when people are aware of them. It is our hope that this report moves that agenda forward by making the “triple win” of soil carbon sequestration for increased productivity. Juergen Voegele Director Agriculture and Rural Development Department The World Bank CARBON SEQUESTRATION IN AGRICULTURAL SOILS . awareness of both the techniques and the benefits remain limited.

Louis Bockel. Pai-Yei Whung. Michael Kane. Ademola Braimoh wrote the report with meta-analyses and research support from Idowu Oladele. Sarah Elizabeth Antos. and Genalinda Gorospe. Shunalini Sarkar. Tim Searchinger. Varuna Somaweera. Dany Jones. This report improves the knowledge base for scaling-up investments in land management technologies that sequester soil carbon for increased productivity under changing climate conditions. Johannes Woelcke. Fionna Douglas. Katie McWilliams. The author is grateful for constructive comments and suggestions from the following peer reviewers: Erick Fernandes. Maria Gabitan. Gunnar Larson. Chuck Rice. Yurie Tanimichi Hoberg. and Ijeoma Emenanjo. Cicely Spooner. and Alex Stoicof provided Geographical Information System and Information Technology support. Johannes Heister. Ramon Yndriago. and Andreas Wilkes. Mark Cackler. John Idowu. Meine van Noordwijk. and Katia Obst carried out the ecosystem simulation modeling. Dipti Thapa. Christine Negra. Ellysar Baroudy. Wilhelmus Janssen. Matthias Seebauer. Sarian Akibo-Betts. Louis Lebel. Kaisa Antikainen. Marjory-Anne Bromhead. EC O N O M I C A N D S E CT OR WORK XI . Patricia del Valle Pérez. while Reza Firuzabadi. Patrick Verkoijen. Many others provided inputs and support including Jurgen Voegele.ACK N O W L E D G ME NT S ACKNOWLEDGMENTS The preparation of this report was managed by the Agriculture and Rural Development (ARD) department.

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ABB R E V I AT I O N S X III ABBREVIATIONS AEZ Agroecological Zone HUM humified organic matter BIO microbial biomass INS inelastic neutron scattering CBP Carbon Benefits Project IOM inert organic matter CSA climate-smart agriculture IPCC Intercontinental Panel on Climate Change DPM decomposable plant material LIBS laser-induced breakdown spectroscopy EX-ACT Ex Ante Appraisal Carbon-Balance Tool MAC marginal abatement cost FAOSTAT Food and Agriculture Organization of the United Nations MMV measurement. monitoring. and verification NPP net primary productivity GEF Global Environment Facility RPM resistant plant material SALM Sustainable Agricultural Land Management SLM sustainable land management UNFCCC UN Framework Convention on Climate Change GHG greenhouse gas GIS geographical information system GPS global positioning system ha hectare EC O N O M I C A N D S E CT OR WORK .

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enhancing its resilience to climate change. A key element of CSA is sustainable land management (SLM). Increasing agricultural productivity. The second exercise was to apply an ecosystem simulation modeling technique to predict future carbon storage in global cropland soils. rising incomes and the increasing proportion of the global population living in urban areas are changing the composition of food demand in fundamental ways. Soil carbon also plays an important role in maintaining the biotic habitats that make land management systems sustainable. both in the role their biomass plays in sequestering carbon and in providing habitat for biodiversity. where the challenge is most acute. It is a major determinant of the soil’s ability to hold and release water and other nutrients that are essential for plants and their root systems to grow. resilient. and reduce agriculture’s contribution to climate change by reducing GHG emissions and sequestering carbon. which is the sector of the global economy that is most vulnerable to the effects of global warming. At the same time. The objective of this report is to improve the knowledge base that informs investment decisions in land management technologies that purposefully sequester soil carbon. Based on these developments. such as livestock that are more resource intensive to produce and process. projections indicate that global food production must increase by 70 percent by 2050. The results EC O N O M I C A N D S E CT OR WORK XV .EX E C U T I V E S U MMARY EXECUTIVE SUMMARY Ensuring food security in a context of growing population and changing climate is arguably the principal challenge of our time. the process by which atmospheric carbon dioxide is taken up by plants through photosynthesis and stored as carbon in biomass and soils. In many African countries. Carbon sequestration. Moreover. Soil carbon has a direct correlation with soil quality. The onus of this challenge falls on agriculture. The current human population of 7 billion will increase to more than 9 billion by 2050. Higher income urban populations have more diverse diets that feature a variety of high-value food sources. can help reverse soil fertility loss. and able to resist degradation. The findings reported are based on three exercises. and reduce the impact of climate change on agricultural ecosystems. The third consisted of a series of estimations of marginal abatement costs and trade-offs to assess the cost-effectiveness of deploying the land management technologies for climate-smart agriculture. Projected increases in demand for food and bioenergy by 2050 have profound implications for the pressure that agriculture wields on forests and other natural ecosystems in the tropics. accounting for one-third of global greenhouse gas (GHG) emissions. and Latin America. it is the central element of most SLM technologies. Asia. limit GHG concentrations in the atmosphere. they become a massive source of GHG emissions. The first was a review of soil carbon dynamics and assessment methods and a meta-analysis of soil carbon sequestration rates in Africa. Because soil is the basic resource in agricultural and forest land use. When they are lost. These ecosystems are vital. and reducing the emissions that come from the agriculture sector are therefore triple imperatives that require alternative sets of practices. strengthen farmers’ resilience to climate change. such as more variable rainfall and more extreme weather-generated events. are one of the principal contributors to climate change. This adds to the challenge of maintaining and preserving the resilience of both natural and agricultural ecosystems. involving the implementation of land-use systems and management practices that enable humans to maximize the economic and social benefits from land while maintaining or enhancing the ecosystem services that land resources provide. Climate-smart agriculture (CSA) seeks to increase productivity in an environmentally and socially sustainable way. food production must increase by more than 100 percent—it must effectively double. agriculture and the changes in land-use that are associated with it.

The first is carbon conservation. in which the growth of agricultural and natural biomass actively removes carbon from the atmosphere and stores it in soil and biomass.XV I EX EC UTIV E S UM M A RY reported in this document complement a number of related publications. which is equal to CARBON SEQUESTRATION IN AGRICULTURAL SOILS . and often limited capacity to implement the techniques. lack of information about the potential of improved techniques. including those emissions that result from land-use change in which carbon stocks become carbon sources as agricultural production expands into natural ecosystems. managing trade-offs. SLM practices are alternatives to conventional agriculture in all three of these paths—conservation. uncontrolled grazing. Working at the landscape level is useful for addressing food security and rural livelihood issues and in responding to the impacts of climate change and contributing to its mitigation. and judicious application of fertilizers can reduce these emissions directly and increase rates of soil carbon sequestration. The amount of support that governments will need to provide by the year 2030 to enable farmers to implement SLM practices are projected at US$20 billion in Africa. the nonavailability of some inputs in the local markets. Profitability In addition to storing soil carbon. The third benefit delivered by SLM is to reduce the emissions of GHGs that emanate from agricultural production. sequestration. Mechanisms for Carbon Enhancement in Agro-Ecosystems Sustainable land management delivers carbon benefits in three important ways.4 trillion for Asia. (Globally. Total private profits by the year 2030 are estimated at US$105 billion for Africa. Maximizing Benefits and Managing Trade-Offs Soil carbon sequestration can be maximized by managing trade-offs across space. Conserving this terrestrial carbon represents a “least-cost opportunity” in terms of climate change adaptation and mitigation and is essential to increasing the resilience of agricultural ecosystems. and plowing and other forms of soil disturbance that release not only carbon dioxide into the atmosphere. and sectors. and lead to the emission of additional GHGs into the atmosphere. and the need for targeted public support. Certain techniques associated with sustainable land management can be incompatible with traditional practices. The Need for Targeted Public Support Without public support for farmers. increase farmers’ vulnerability to the effects of climate change. and reductions in GHG emissions. and wetlands remain stored as carbon stocks. $41 billion in Latin America. These conventional agricultural practices include deforestation. and $1. the diffusion of new technologies relies on a level of social capital and experience with collective action that farmers simply do not yet have. At least four key messages emerge over the course of this report. Barriers to Adoption and Up-Front Costs The adoption of sustainable land management practices can face a variety of socioeconomic and institutional barriers. barriers to adoption. grasslands. The Dynamics of Soil Organic Carbon Different ecosystems store different amounts of carbon depending on their species compositions. In some instances. soil types. The second benefit is carbon sequestration. While it capitalizes more purposefully on the positive impacts of conservation and sequestration. and other biophysical features. sustainable land management technologies can be beneficial to farmers because they can increase yields and reduce production costs. volumes of carbon are generally measured in gigatonnes [Gt]. $274 billion for Latin America. the burning of biomass. and these relate to profitability. relief. draining of wetlands. water management. time. climate. but also nitrous oxide and methane—GHGs with extremely high impacts on global warming. and $131 billion in Asia. in which the large volumes of carbon stored in natural forests. Investment in soil quality improvement practices such as erosion control. including empirical lessons from recent project examples and policy briefs that were used as inputs at the Durban Climate Change Conference in November 2011. poor agricultural land management will intensify land degradation. its reversal of agriculture’s negative impacts also presents profound contrast with conventional practices. These include the need for significant up-front expenditures on the part of poorer farmers.

EC O N O M I C A N D S E CT OR WORK 16 151.5 8 4.0 330 Temperate grasslands 12.5 9 3. Robert. Soils hold more carbon than plant biomass (or vegetation) and account for 81 percent of the world’s terrestrial carbon stock.0 295 97. from 100 Gt in temperate forests to 471 Gt in boreal forests. (2000).5 15 6. et al. for instance.0 191 96.5 66 20.7 88 15. any large-scale melting caused by global warming will release massive volumes of carbon into the atmosphere.9 159 Boreal forests 13.011 2.0 304 Deserts 45.8 240 3 2.0 264 80.1 100 62.3 559 Tropical savannas 22.7 471 84. or metric tons in the United States. Because much of the soil organic carbon stored there is permafrost and wetlands.3 127 Wetlands 3.5 6 4.1: Terracing and Landscape Management in Bhutan Source: Curt Carnemark/World Bank.2 466 2. ranging. with the exception of limited areas selected for forest management.3 225 93.6 VEGETATION PROPORTION (%) SOILS PROPORTION (%) TOTAL 212 49. 1 billion tons.0 199 Tundra 9. Boreal ecosystems are a particular concern.5 216 50.7 121 95. Soil carbon stocks also vary by ecosystem.4 59 37. TABLE E1: Carbon Stocks in Vegetation and Top 1 Meter of Soils of World Biomes CARBON STOCKS (Gt C) AND PROPORTION IN THE ECOSYSTEM (%) BIOMES AREA (MILLION km2) Tropical forests 17.7 131 Croplands Total Proportion (%) Source: Watson.) The amount of carbon stored in plant biomass ranges from 3 Gt in croplands to 212 Gt in tropical forests (table E1).477 19 81 100 . Conservation and protection are therefore widely recognized as major priorities.3 128 97.5 428 Temperate forests 10.EX E C U T I V E S U MMARY X V II PHOTO E.

Under undisturbed natural conditions. oil.24 North America 28. The soil carbon pool is more than 3 times the size of the atmospheric pool (760 Gt) and about 4.04 Gt per year for Oceania to 0. Climate has both direct and indirect effects on attainable sequestration.8–1. and leaching. Actual carbon sequestration is determined by land management factors that reduce carbon storage such as erosion. vegetation.2 Gt of emitted carbon per year. while the soil inorganic carbon and elemental pools make up the remaining 950 Gt (Batjes 1996). The soil organic carbon pool represents a dynamic balance between gains and losses. Theoretically. The potential carbon sequestration is controlled primarily by pedological factors that set the physico-chemical maximum limit to storage of carbon in the soil. 50 years ago they removed 60 percent.2 0.92 Gt of carbon per year through soil erosion. and proportion of coarse fragments.02 to 0.6 Gt for Oceania to 74.60 and 0. residue removal. Gt C/YEAR) EMISSION (20 PERCENT OF DISPLACED SOIL CARBON.04–0. Gt C/YEAR) Africa 38.16 Europe 13. biomass burning. the soil organic carbon pool comprises 1.2 0. vegetation. only 50 to 66 percent of this capacity is attainable through the adoption of sustainable land management practices. Net primary productivity (NPP)—the rate of photosynthesis minus autotrophic respiration—is the major factor influencing attainable sequestration and is modified by above-ground versus below-ground allocation. 201 Gt of soil is lost to erosion. and oceans.0 Gt for Asia (table E2). Africa.7 and 2.44 South America 39. The global carbon cycle describes the transfer of carbon in the earth’s atmosphere. excessive fertilizers. residue removal.0 0. Land management practices that increase carbon input through increasing NPP tend to increase the attainable carbon sequestration to nearer to the potential level. Soils are critically important in determining global carbon cycle dynamics because they serve as the link between the atmosphere.04 201.0 1. Decomposition rate increases with temperature but decreases with increasingly anaerobic conditions.30 to 0.6–0. However. Rapidly growing emissions are outpacing the growth in natural sinks (lands and oceans). organic matter decomposition. Attainable carbon sequestration is determined by factors that limit the input of carbon to the soil system.1 0. Globally.16–0. and drainage.9 0. Such factors include soil texture and clay mineralogy. (2003). the soil carbon pool (also referred to as the pedologic pool) is estimated at 2.1 Gt carbon per year. Out of this.5–2. and drainage of peat lands) is between 0. This corresponds to carbon emissions ranging from 0.08 7. The efficiency of oceans and lands as carbon dioxide sinks has declined over time. accelerated soil erosion leads to progressive depletion of soil carbon.0–6.8–1.2–0. R. the potential soil carbon sequestration capacity is equivalent to the cumulative historical carbon loss. and oceans.24 Asia 74. The two most important anthropogenic processes responsible for the release of carbon dioxide into the atmosphere are the burning of fossil fuels (coal.XV I I I EX EC UTIV E S UM M A RY TABLE E2: Estimates of Erosion-Induced Carbon Emission Across World Regions GROSS EROSION (Gt/YEAR) SOIL CARBON DISPLACED BY EROSION (2 TO 3 PERCENT OF SEDIMENT.4 0. depth.500 Gt up to a 2-m depth.2 0.16–0. The annual rate of soil loss ranges from 7. CARBON SEQUESTRATION IN AGRICULTURAL SOILS . and South America emit between 0.02–0.8 0. The amount changes over time depending on photosynthetic C added and the rate of its decay. tillage operations.550 Gt. soils.6 0.4 0. tillage.2 REGION Oceania Total Source: Lal.44 Gt per year for Asia. and natural gas) and land use. aeration. Soil erosion is the major land degradation process that emits soil carbon.8 to 1.1 0.5 times the size of the biotic pool (560 Gt). Globally. The current rate of carbon loss due to land-use change (deforestation) and related land-change processes (erosion. Asia. bulk density.30–0.8–1.12–0.1 4. These sinks currently remove an average of 55 percent of all anthropogenic carbon dioxide emissions. corresponding to 0. inputs of carbon from litter fall and root biomass are cycled by output through erosion. Agricultural soils must be prevented from being washed into streams and rivers where the relatively stable soil carbon pools are rapidly oxidized to carbon dioxide.2 0. Because soil organic matter is concentrated on the soil surface.1–0.

Direct methods are more precise and accurate but also more time and labor intensive as well as very expensive. and estimation of the marginal cost of carbon sequestration. soil. In the case of carbon projects. is the next largest terrestrial carbon flux following photosynthesis. When other factors are at optimum. Soil carbon assessment methods can be broadly classified into direct and indirect methods. Approaches to Soil Carbon Assessment Soil carbon assessment in different parts of the world requires methods that are appropriate to the circumstances. and remote sensing. adaptation. While LIBS and INS technologies are still in their infancy. and scaling-up the results to the entire project area. leading to reduced crop production and decreased resilience of the soil ecosystem. the cellulose absorption index. but most of its challenges can be addressed through an appropriate design that accounts for soil spatial variation. excessive respiration. Ensuring this comparability warrants serious international priority. development of measurement protocols. crop yields and location. and cost-effectiveness over conventional ex situ methods. credible and cost-effective techniques of monitoring changes in soil carbon still need to be developed. One of the more important indirect methods involves the use of simulation models that project changes in soil organic carbon under varying climate. These parameters are fed into biogeochemical models to predict soil carbon sequestration. All of this is critical information used for input into models. and inelastic neutron scattering (INS). Scaling-up to larger areas requires integration from a variety of sources including field measurements. and mitigation. they are a cost-effective means of estimating GHG emissions in space and time under a wide range of biophysical and agricultural management conditions. These include selection of landscape units suitable for monitoring soil carbon changes. geographical information systems. models. has been used to infer tillage intensity and residue quantity.EX E C U T I V E S U MMARY Soil respiration. management history. derived from remote imaging spectroscopy. existing databases. the flux of microbially and plant-respired carbon dioxide. and soil organic matter decomposition. spatially explicit biogeochemical modeling. soil properties. The variety of methods that have been developed and tested for use in different countries raises concerns about their comparability. Each context will require a differing degree of granularity and measurement set to assess uncertainty in the estimates. leaf area index. Indirect methods are needed to fill knowledge gaps about the biogeochemical processes involved in soil carbon sequestration. The most established type of direct soil carbon assessment entails collecting soil samples in the field and analyzing them in the laboratory using combustion techniques. Monitoring and verifying soil carbon sequestration at the project or regional scale require five activities. estimated at 75 to 100 Gt carbon per year. and water management can optimize soil respiration in addition to improving soil carbon leading to the triple win of enhanced agricultural productivity. The degree and nature of sampling depend on the objectives of the carbon assessment objective. application of manure. near-IR spectroscopy. measurement of bulk density. A small change in soil respiration can significantly alter the balance of atmospheric carbon dioxide concentration compared to soil carbon stores. Conventional tillage leads to the destruction of soil aggregates. sampling depth and volume. Multitemporal moderate resolution remote sensing such as the Landsat Thematic Mapper and Moderate EC O N O M I C A N D S E CT OR WORK X IX . for instance. Some in situ soil carbon analytical methods are being developed with the objective of offering increased accuracy. use of remote sensing to estimate soil organic carbon controlling parameters. depending on whether carbon content in soil samples is directly measured or inferred through a proxy variable. whether. The in situ soil carbon analytical methods include mid-infrared (IR) spectroscopy. Soil respiration is a potentially important mechanism of positive feedback to climate change. Protocols for temporally repeated measurements at fixed locations will generally include stratification and selection of sampling sites. other ancillary field measurements. laboratory analyses. tillage practices. use of cover crops (green manure). particularly in the context of developing countries in which land resources data are scarce. laser-induced breakdown spectroscopy (LIBS). Remote sensing can provide information on net primary productivity. precision. Although simulation models can have limited accuracy. The data can be particularly useful in scaling-up site-specific information to larger scales of magnitude. crop rotations. and availability of historical data. IR spectroscopy has proven valuable in developing soil spectral libraries and for rapid characterization of soil properties for soil quality monitoring and other agricultural applications in developed and developing countries. conservation tillage. and management conditions. and amounts of crop residues. Field sampling is technically challenging. Recently. Indirect estimation of soil organic carbon changes over large areas using simulation models has become increasingly important. the assessment is used for national or regional accounting or for a carbon offset project. The selection of landscape monitoring units is based on the responsiveness of the area to land management practices as determined by climate. use of deep-rooted crops.

referred to as Sustainable Agricultural Land Management (SALM). thereby indicating the overall effects on the carbon balance. and Reporting System. soil nitrous oxide emissions. rice methane emissions. The Agriculture and Land Use National Greenhouse Gas Inventory Software tool was recently developed by Colorado State University to support countries’ efforts to understand current emission trends and the influence of land-use and management alternatives on future emissions. A detailed analysis of lessons learned in testing EX-ACT in World Bank agriculture projects can be found in a separate report. The BioCarbon Fund of the World Bank has also developed a methodology to encourage adoption of sustainable land management practices by small-scale farmers in developing countries.2: Crop Residue Management in Irrigated Fields in Indonesia Source: Curt Carnemark/World Bank. Accounting. as well as non-CO2 GHG emissions from biomass burning. EX-ACT can provide ex ante assessments of the impact of agriculture and related forestry. Indonesia’s National Carbon Accounting System.500 mm.XX EX EC UTIV E S UM M A RY Resolution Imaging Spectroradiometer can provide information such as land-use and land-cover change. livestock. The tool can be used to estimate emissions and removals associated with biomass C stocks. The Food and Agriculture Organization of the United Nations has developed the Ex Ante Appraisal Carbon-Balance Tool (EX-ACT) to assess GHGs in the agricultural sector. and New Zealand’s Carbon Accounting System. Examples of national carbon accounting system and tools include Australia’s National Carbon Accounting System. irrespective of land management practices. enteric methane emissions. The methodology. and water development projects on GHG emissions and carbon sequestration. fisheries. Canada’s National Forest Carbon Monitoring. In this study. soil C stocks. PHOTO E. Factors Affecting Soil Carbon Sequestration Climate significantly influences large-scale patterns of soil carbon sequestration. for the most part. crop rotations. CARBON SEQUESTRATION IN AGRICULTURAL SOILS . provides a protocol for quantifying carbon emissions and removals and includes guidelines for identifying baseline scenario and assessing additionality in all carbon pools relevant to sustainable land management projects. restricted to industrialized countries and a handful of developing countries. higher sequestration rates were observed in the wettest locations with annual precipitation above 1. and manure methane and nitrous oxide emissions. Monitoring trends in soil carbon over a large geographical area through repeated sampling is. and soil moisture. which can markedly improve our ability to scale-up soil carbon assessments.

The greenhouse mitigation of manure is much higher at about 2. In Africa and Latin America. sugarcane.g. Land emissions are the differences between emissions of nitrous oxides and methane by conventional and improved practices. Information on carbon sequestration potential of a location can be derived by point-and-click or by searching using place names.5 t CO2e per ha per year across the three regions.2 to 3. Users can download data from the database and integrate them with other GIS information to estimate soil carbon stock changes for different agricultural projects.4 t CO2e per ha per year. and they also help in improving soil aggregate stability and protecting the soil from surface runoff. Differences in soils. The Internet GIS database provides per-hectare estimates of soil carbon sequestration under different land management practices for a period of 20 to 25 years. Cover crops improve soil quality by increasing soil organic carbon through their biomass. and cropping systems also affect carbon sequestration under crop rotation. These rates represent the marginal carbon benefit of mulching or incorporating residues relative to burning. Most of the potential soil carbon sequestration takes place within the first 20 to 30 years of adopting improved land management practices. Soils with higher clay content sequester carbon at higher rates. Process emissions are those arising from fuel and energy use.13 t CO2e per ha per year for Asia and 0. climate. The tool comprises several land management scenarios reflecting situations typically encountered in agricultural projects.29 t CO2e per ha per year for Africa.7 to 2. the highest rates of sequestration are achieved in the intermediate term.9 to 3. Cover crops and crop rotation are key complementary practices for successful implementation of no-tillage. maize or sorghum followed by legumes) or a variety from the previous crop. carbon sequestration rates and variability are highest on inceptisols—relatively young soils that constitute about 9 percent of soils in the tropics.worldbank.7 to 1. No-tillage and residue management generated abatement rates ranging from 0. The emissions associated with the technologies are classified as land emissions and process emissions. rice. The abatement rate is expressed in tons of carbon dioxide equivalent (t CO2e) per hectare (ha) per year. There is a tendency toward higher carbon sequestration rates in triple cropping systems. They also sequester carbon in the soil. GHG abatements of cover crops were 1. grazing.4 t CO2e per ha 1 The World Bank has posted a useful geographical information system tool on the Internet that summarizes the results of a series of ecosystem modeling exercises (see http://www-esd. Crop rotation is the deliberate order of specific crops sown on the same field. In Asia. Improved irrigation generated low to moderately high abatement rates (0.1 Greenhouse Gas Mitigation by Sustainable Land Management Technologies The climate benefits of sustainable land management technologies are measured by the net rate of carbon sequestration adjusted for emissions associated with the technologies—a measurement referred to as the abatement rate. Timing is another factor that warrants careful consideration when introducing improved land management practices that increase carbon sequestration. and other grain crops. and removal of the residues for other uses.EX E C U T I V E S U MMARY There was also a trend to lower sequestration rates in the coolest (mean annual temperature less than 20°C) and warmest (mean annual temperature greater than 30°C) conditions. and the planned rotation may be for 2 or more years.2 to 2..5 t CO2e per ha per year. with lower or even negative rates in the short term. Supplemental irrigation and water harvesting are needed to minimize production risks in dry land agriculture. while semi-humid areas have higher sequestration rates than their semi-arid counterparts. formed principally in humid tropical zones under rain forest. the highest sequestration rates and variability are observed in oxisols.org/SoilCarbonSequestration/). Sites in warmer and middle temperature regions tend to accumulate soil carbon more rapidly than those in colder regions. scrub. while those of crop rotation were 0. Commonly applied residues on croplands include biomass from trees. In Latin America. With most practices.7 t CO2e per ha per year across the regions. EC O N O M I C A N D S E CT OR WORK XXI . The succeeding crop may be of a different species (e. The patterns of change in sequestration rates are nonlinear and differ between major types of practices. or savanna vegetation. although variation is high.23 t CO2e per ha per year compared to 0. Increases in productivity from nitrogen fertilizers need to be considered against the increased emission of GHGs from soils as well as the energy-related emissions associated with the fertilizer’s production and transport. Oxisols comprise about 24 percent of tropical land mass and are typically found on old landscapes that have been subject to shifting cultivation for some time. the abatement rate of inorganic fertilizer is −0. Soil type is significant to soil carbon sequestration as well.

ch e im mic pr al ov fe di ed rtili ve irr ze ig r r in sify ati te o r ns ot n gr re ify atio as du ro n sla ce ta nd d.er till to cro -p re er ps sid en ue n m m ial an a n pa u st age re ur m een in to-f t clu or e in de t st te r e r pa c cr es st rop opp ur e.-to. CARBON SEQUESTRATION IN AGRICULTURAL SOILS .tio -t gr n no o-p azin or lant g re ati du on c an c nu ov ed al.es rie cr i rs op n f af far ield fo m r a es in im lley tat g pr fa ion ov rm ed in fa g ll bi ow oc ha r XXI I EX EC UTIV E S UM M A RY FIGURE E1: Abatement Rates of the Land Management Practices (t CO2e Per Hectare Per Year) 12 10 Africa 8 6 4 2 0 18 16 14 Asia 14 12 10 8 6 4 2 0 16 Latin America 12 10 8 6 4 2 0 -2 Source: This study.ing to fo r -p lan est ta ti bi on oc ha r no ica o l fe re int r re rtil s e d iz ap idue nsi uce er f pl ica ma y ro d ti tio na tat ll n g io re of em n du m en ce ulc t d.he gr s c cr op ove azin -to r c g -g ro ra ps im ss pr ov m lan ed a d n an in irri ure g c n l in ua ud at i te lns to e t on ive -pe ree w at ve ren s er ge ni ha ta al b in rve les te rs rc tin r cr op bi opp g -to ofe ing -p r cr lan tiliz op ta er -to tio -fo n r bi est oc ha r m ch e ro ch ta em tio i n ca in l f te er ns til ifi ize ro ca r ta tio r e tio s id n n di m ue ve u s rs lch ifi e c s no atio co til n ve lag ot rc e he ro rs ps m o pa il a t an st m er ure ur en ra e d cin w imp em g at ro en er v ts h e cr in arv me os t e nt e in s s rcr stin clu lo op g de pe pi tre tre /bar ng e.

Apart from energy-related emissions.3 to 15. integrated land-use systems combining trees and shrubs with crops and livestock.6 to 6.5 t CO2e per ha per year. 8. while conversion of cropland to plantation generated an abatement of 5. Pasture improvement generated an abatement of 3. on average.3 to 6.21 t CO2e per ha per year.3 t CO2e per ha per year.3: Water Management in a Field in India Source: Ray Witlin/World Bank. biochar production should not deplete the soil of the crop residues needed to protect against erosion and increase soil resilience.4 to 5.9 to 4. the process of concentrating runoff from a larger area for use in a smaller target area.7 t CO2e per ha per year). By definition. Rather.7 t CO2e per ha per year. In general. 7. EC O N O M I C A N D S E CT OR WORK X X III . Abatement rates of agroforestry systems. Conversion of cropland to forest or pasture to plantation resulted in an abatement of 6.7 for improved fallow (involving the use of fast-growing trees to accelerate soil rehabilitation). preferably leguminous trees or shrubs).EX E C U T I V E S U MMARY per year).5 for tree-crop farming. This is due to the relatively large time-averaged biomass of trees compared to crops. a critical issue for soil carbon sequestration activities in irrigated areas is reduced emissions of methane from rice fields. Application of biochar. The GHG abatement of water harvesting. whereas conversion of cropland to grassland produced GHG mitigation of 2.6 t CO2e per ha per year. However. Process and land emissions under irrigation can significantly offset gains from carbon sequestration. they should be based on whole farm systems analysis that comprehensively assesses the productivity. resulted in the highest overall GHG abatement rate (10.6 for alley farming (the growing of crops simultaneously in alleys of perennial. PHOTO E. Decisions to adopt any of the land management practices should not be based solely on their respective climate mitigation benefits. The average abatement rates in t CO2e per ha per year are 7. and 4.3 for intercropping (the growing of crops near existing trees).7 to 7. 4. land-use changes away from cropland to agroforestry or plantations provide more convincing examples where it is useful to think of both aboveand below-ground sequestration rates at the same time and possible trade-offs or interactions between them.8 t CO2e per ha per year. Mid-season drainage is a viable practice to reduce such emissions. The impacts of land-use changes on tree-based systems are also relatively large. but its impact on crop productivity and soil resilience is still uncertain. Terracing and construction of slope barriers on sloping lands for soil and water conservation produced abatements of 2. averaged 3. are fairly high. most of the potential impact of changes in agricultural practices on carbon stocks is below ground.7 for croplands where trees are introduced.

will most likely generate optimum social benefits. but relatively high labor inputs are required to reduce competition effects of trees from negatively impacting crop growth. yields have doubled for maize and increased by 60 percent for cotton compared to the conventional tillage system. however. Farmers also frequently reported significant crop yield increases for maize. and increases crop yields. taken within a wider socioeconomic context. due to nitrous oxide emissions associated with high application rates of nitrogen fertilizers and fossil fuel–based emissions associated with fertilizer production and transportation. Excessive fertilizer use is less environmentally friendly. Inorganic fertilizers also show relatively high profits because they provide nutrients that can be readily absorbed by plants. They reduce the amount of land available for cultivation in the short run but can lead to overall increases in productivity and improved resilience in the long run.XXI V EX EC UTIV E S UM M A RY PHOTO E. Farm-scale management decisions. Judicious fertilizer application counters soil nutrient depletion. A plot of profit versus carbon sequestration reveals synergies in two agroforestry systems—intercropping and alley farming (top right quadrant of figure E2). Profitability of Soil Carbon Sequestration In addition to storing soil carbon. land management technologies in the lower right quadrant have high mitigation potentials but are modestly profitable. cotton. and environmental load of the system. and groundnut in agroforestry systems. on-farm resource use. Increasing food security under a changing climate requires the analysis and identification of the land management technologies that maximize synergies and minimize trade-offs. Afforestation. improved fallow (including trees in croplands). particularly the influence of public policy and markets. reduces deforestation and expansion of cultivation to marginal areas. The pattern of increase in yield. and establishing barriers across sloping areas tend to take land out of production for a significant period of time. In figure E2. millet. however. Capitalizing on Synergies and Managing Trade-Offs in Soil Carbon Sequestration Synergies occur when there is a positive correlation between carbon sequestration and profitability (where profitability refers to the net present value of implementing the land management practices). In Zambia. The time-averaged. Increases in crop yields derive from the ability of the land management technologies to maintain soil organic matter and biological activity at levels suitable for soil fertility. sustainable land management technologies can be beneficial to farmers by increasing yields and reducing production costs. above-ground CARBON SEQUESTRATION IN AGRICULTURAL SOILS .4: Maize Growing under Faidherbia Albida Trees in Tanzania Source: World Agroforestry Centre. varies from crop to crop. sorghum. The profitability of no-tillage systems results mainly from the reduced labor requirement for seedbed preparation and other tillage operations compared to conventional tillage systems. Trade-offs occur when attempts to increase carbon storage reduce profits.

biomass of crop residues and other technologies in the lower left quadrant of figure E2 is relatively small compared to that of agroforestry systems. the biomass of crop residues does not accumulate easily. EC O N O M I C A N D S E CT OR WORK .000 No-tillage Inorganic fertilizer Intercropping 100 Alley farming Manure Cover crops Soil amendments Crop residues Include trees Terracing 10 Rotation intensification Rotation diversification Afforestation Tree crop farming Rainwater harvesting Improved fallow Cross slope barriers 1 0 2 4 6 8 10 carbon dioxide sequestered (ton per hectare per year) Source: This study. The Biomass Is Smaller Compared to that of Agroforestry Systems Source: Curt Carnemark/World Bank. Yields also increase with manure application and accumulation of soil carbon. FIGURE E2: Trade-Offs Between Profitability and Carbon Sequestration of Sustainable Land Management Technologies profit per tone of carbon dioxide sequestered (US $) 1. Judicious fertilizer application increases crop yields and profitability.EX E C U T I V E S U MMARY XXV PHOTO E. Manure is less profitable than inorganic fertilizer because of the labor costs associated with collecting and processing manure (top left quadrant of figure E2). The relatively high profitability of no-tillage derives primarily from the decrease in production costs after the establishment of the system. but with patterns that depend on crop type.5: Crop Harvesting in Mali. Also. resulting in lower mitigation benefits.

fisheries. and water at local. figure E3) reflects the use of subsidies in spurring farmers’ access to the technology. investments in improved land management. Thus. fertilizer subsidies are appropriate in situations when the economic benefits clearly exceed costs. Technologies that involve significant change in land use (such as afforestation and improved fallows) and landscape alteration (such as terracing and cross-slope barriers) incur high public costs but generate low private benefits (lower right quadrant of figure E3). agriculture. difficult targeting. crop rotation. cover crops. The low profits suggest that farmers may be reluctant to privately invest in these technologies. input subsidies. benefits more farmers. The relatively high public cost of inorganic fertilizer (top right quadrant. respectively). Public support that focuses on research. Sustainable land management interventions should be planned and implemented in a coordinated manner across space. and the support helps improve targeting through market-smart subsidies while providing impetus for private sector input development. Working at the landscape level within an ecosystems approach is useful for addressing food security and rural livelihood issues and in responding to the impacts of climate change and contributing to its mitigation. and rainwater harvesting with lower profits and also manure and no tillage that generate relatively higher profits require minimal government support (lower left and upper left quadrants of figure E3. carbon storage. and pollination. These technologies generally have low mitigation potentials. FIGURE E3: Relationship Between Private Benefits and Public Costs private benefit (per tonne of carbon dioxide sequestered) 1000 No-tillage Inorganic fertilizer Intercropping 100 Alley farming Manure Cover crops Terracing Include trees Crop residues Crop rotation 10 Afforestation Tree crop farming Improved fallow Rainwater harvesting Cross slope barriers 1 0 3 5 8 10 13 public cost ($ per tonne of carbon dioxide sequestered) Source: This study.XXV I EX EC UTIV E S UM M A RY The trade-offs exhibited by the land management technologies have important implications for land-use decision making. and sectors. The landscape approach entails the integrated planning of land. and mitigation benefits in agriculture. matching grants. The landscape approach provides a framework for the better management of ecosystem services. The pattern of public support is as crucial as the amount of support for full realization of productivity. and regional scales to ensure that synergies are properly captured. and land tenure rather than on input support is generally more effective. biodiversity protection. and is more sustainable in the long run. adaptation. and loan guarantees. vouchers. freshwater cycling. Public Costs of Soil Carbon Sequestration Public cost refers to government support toward the implementation of land management practices. They include investments in seeds and seedlings. watershed. and crowding out of commercial sales. Crop residues. Strong public involvement in these technologies is required given their relatively high mitigation potentials. Fertilizer subsidies are associated with high fiscal costs. extension services. the subsidies help achieve social rather than economic objectives. such as agricultural productivity. CARBON SEQUESTRATION IN AGRICULTURAL SOILS . and other administrative costs. Examples of market-smart subsidies include demonstration packs. time. forests.

their adoption faces many socioeconomic and institutional barriers: Most of the land management technologies require significant up-front expenditure that poor farmers cannot afford. and impact of such land management technologies.3 B1 5.4 B1 2. and Public Costs of the Land Management Technologies by 2030 SCENARIO TECHNICAL POTENTIAL (MILLION TONS CO2-eq) PRIVATE BENEFITS (US$. Better market prices for crops and other agricultural produce are crucial.538 288.224.310.0 Gt CO2-eq for Asia (table E3).4 trillion in Asia.097 319. Notes: B1 = a world more integrated and more ecologically friendly.9 22.321 273. Secure land rights is a precondition for climate-smart agriculture as it provides incentive for local communities to manage land more sustainably.8 A1b 2.007 1. BILLION ) Africa B1 3.4 19.977 1.259. while total public costs range from US$20 billion in Africa to $160 billion in Asia.5 131.678 111.6 19.926 120. their adoption is often resisted.448 105.8 A2 3. and the costs of soil carbon sequestration by 2030 depend on the emission scenarios influenced by a wide range of driving forces from demographic to social and economic developments. TABLE E3: Technical Mitigation Potential. A1b = a world more integrated with a balanced emphasis on all energy sources.425 279.368.4 55.3 143.6 B2 7. lack of information on the potentials of alternative techniques of farming and limited capacity is a major constraint in many developing countries. Private Benefits.6 A1b 3.678 1.1 159. B2 = a world more divided but more ecologically friendly. the nonavailability of inputs in the local markets can be a significant obstacle.3 A1b 6. Barriers to the Adoption of Sustainable Land Management Practices Despite the fact that improved land management technologies generate private and public benefits. diffusion.3 A2 3.8 44.EX E C U T I V E S U MMARY X X V II The overall biophysical mitigation. A2 = a world more divided and independently operating self-reliant nations. BILLION ) PUBLIC COSTS (US$. EC O N O M I C A N D S E CT OR WORK . Total private profits range from US$105 billion in Africa to $1.4 42.8 150.388 1.7 B2 3. Factors affecting adoption tend to be more specific to the land management technologies. However.4 20.9 B2 2. potential savings. Ill-defined land ownership may inhibit sustainable land management changes. when technologies are inconsistent with community rules and traditional practices. improved availability of inputs is a necessary but insufficient condition for adoption of land management practices.7 A2 6. The absence of collective action will hinder successful uptake.505 108. Table E4 suggests that lack of credit and inputs and land tenure problems are by far the most important factors for adoption across the range of technologies.3 Gt CO2-eq for Latin America to 7.1 Asia Latin America Source: This study. and willingness and ability to work together is crucial for many technologies such as improved irrigation and communal pastures. The total mitigation potential varies from 2.8 40.

residue management.. regional platforms. strategies. and use of cover crops is highly knowledge intensive. For instance. CARBON SEQUESTRATION IN AGRICULTURAL SOILS . Key * = Low importance.. 1. Countries must be prepared to access new and additional finance. At the 17th Conference of Parties to the UNFCCC in Durban. and investment plans should be strengthened to form the basis for scaling-up investments for climate-smart agriculture. *** = High importance. 2. Mekdaschi Studer. As a result. Hauert. Behavioral change through education and extension services is required to enable change-over to improved land management technologies. the international community has recognized the importance of integrating agriculture into the ongoing negotiations on the international climate change regime. M. Existing national policies. the farming system involving no-tillage. A more practical and thorough picture makes it possible for agriculture to be rewarded for its positive environmental impacts and to be an integral part of the solution as well as part of the problem. 2011. Learning hubs. 2011. The knowledge base of land management practices at the local level can be also improved through careful targeting of capacity development programs. conservation agriculture. H. carbon sequestration may not reach the optimal level from a social point of view unless some mechanisms exist to encourage farmers. requiring training and practical experience of those promoting its adoption. P. Liniger.. C. This is vitally important because agriculture needs to be fully incorporated into adaptation and mitigation strategies. scientific research. Redressing this omission promises to foster a more balanced perspective in which food security is not necessarily at odds with climate change adaptation and mitigation (an unworkable conflict in which longer term environmental concerns are virtually guaranteed to universally lose out politically to the more immediate concern of food supply). Strengthen the capacity of governments to implement climate-smart agriculture. Readiness for carbon sequestration and climate-smart agriculture can be achieved through improved extension services and training in relevant land management technologies for different locales. thus. While the negative impacts of agricultural production in terms of land-use change and GHG emissions were reasonably well covered by the convention. progress in incorporating it into the UN Framework Convention on Climate Change (UNFCCC) has been slower than many people hoped for. Given the tremendous significance that agriculture has for the global climate. South Africa. Sustainable Land Management in Practice—Guidelines and Best Practices for SubSaharan Africa. There is a need to build the technical and institutional capacity of government ministries to implement climate-smart agriculture programs. the real and potential contributions the sector can and does make in terms of sequestering carbon in agricultural biomass and soils were for the most part omitted. the parties asked the UNFCCC Subsidiary Body for Scientific and Technological Advice to explore the possibility of a formal work program on agriculture. Policy Implications Private benefits that drive land-use decisions often fall short of social costs. R. Global cooperative agreement. south-south knowledge exchange. and technical support mechanisms may increase innovation and facilitate adoption of improved land management technologies. in November 2011. and Gurtner. ** = Moderate importance. World Overview of Conservation Approaches and Technologies and Food and Agriculture Organization of the United Nations. Some public policies that can potentially incentivize carbon sequestration include the following options.XXV I I I EX EC UTIV E S UM M A RY TABLE E4: Relative Importance of Different Factors for Adopting Improved Land Management Practices LAND MANAGEMENT TECHNOLOGY INPUTS/ CREDITS MARKET ACCESS TRAINING/ EDUCATION LAND TENURE RESEARCH INFRASTRUCTURE Inorganic fertilizer *** ** ** ** * ** Manure ** ** * ** * ** Conservation agriculture ** ** *** ** ** * Rainwater harvesting ** ** ** *** ** ** Cross-slope barriers ** * ** ** ** * Improved fallows ** * * *** ** * Grazing management *** *** ** *** ** * Source: Synthesized from Liniger et al.

Nationally owned climate-smart agricultural policies and action frameworks will increase the adoption of sustainable land management practices. grant funding or loans may be more suitable to overcoming adoption barriers. This private investment can be targeted to some degree as well. Bundling agricultural credit and insurance together and providing different forms of risk management such as index-based weather insurance or weather derivatives are areas of private investment that can be encouraged through public policy and public-private partnerships. 4. A blend of public. particularly when government priorities translate clearly into business opportunities and certain areas of investment are looked upon favorably by public officials and institutions. and development finance will be required to scale-up improved land management practices. payment for an ecosystem services scheme could be used to support farmers and break the adoption barrier. EC O N O M I C A N D S E CT OR WORK X X IX . 5. establishing tree plantations. Particular attention should go to encouraging private financial service providers to tailor instruments that enable farmers who adopt SLM practices to overcome the barriers described above.EX E C U T I V E S U MMARY 3. Public investment can also be used to leverage private investment in areas such as research and development. and involving the private sector in climate-smart agriculture and sustainable land management is the other. Boost financial support for early action. and developing improved seeds and seedlings. For technologies such as conservation agriculture that require specific machinery inputs and significant up-front costs. In some cases. Introducing policies and incentives that provide an enabling environment for private sector investment can increase overall investment. While this may appear a tall order in countries with severe budget constraints. relatively affordable technologies that generate quick and demonstrable benefits may warrant priority and potentially establish some of the channels through which more sophisticated technologies are dispersed in the future. finite public resources can be more selectively targeted using the criteria given above—prioritizing technologies that generate no short-term returns and those that most effectively address the barriers that prevent prospective adopters from moving forward. Raise the level of national investment in agriculture. private. However. For technologies that generate significant private returns. Integrating sources of climate finance with those that support food security may be one of the most promising ways to deliver to climate-smart agriculture the resources it requires. Create enabling environments for private sector participation. There is also the potential for carbon finance to support farmers during the initial period before the trees in agroforestry systems generate an economic return. public investment is only one sphere.

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water. The net increase in agricultural land during the 1980s and 1990s was more than 100 million ha across the tropics. There are about 925 million food-insecure people in the world—about 16 percent of the population in developing countries. creating a demand for a more diverse diet that requires additional resources to produce. 38% Biomass burning. Over this period. Under optimistic lower end projections of temperature rise. 32% . Agriculture is the primary driver of deforestation in many developing countries. while increased incidence of droughts and floods may lead to a sharp increase in prices of some of the main food crops by the 2050s. in addition to maintaining and. 7% Forestry 17% Rice production.1 INTRODUCTION FOOD SECURITY UNDER A CHANGING CLIMATE Ensuring food security under changing climate conditions is one of the major challenges of our era. and energy will intensify in an attempt to meet the need for food. Competition for land. and Lobell 2010). Smith et al. The interactions between ecosystems and climate change are complex. and the full implications in terms of productivity and food security are uncertain (Gornall et al. Agriculture is highly vulnerable to climate change and needs to adapt to changing climate conditions. 2010) The agriculture sector has a pivotal role to play in mitigating greenhouse gas (GHG) emissions. 2008. Various projections suggest that global food requirements must increase by 70 to 100 percent by 2050 (Burney. Davis.1: Contribution of Different Sectors to Greenhouse Gas Emissions Buildings 8% Manure mgt. 11% Industry 19% Agriculture 14% Energy 26% Waste 3% Transport 13% Source: IPCC 2007. About 55 percent of the new FIGURE 1. Agriculture and land-use change currently account for about one-third of total emissions (figure 1. Global population will increase from 7 billion currently to over 9 billion people by 2050. and fiber and will contribute to economic development and poverty reduction. Climate change will also impact agriculture through effects on pests and disease. globalization may further expose the food system to the vagaries of economic and political forces. 12% Enteric fermentation.1 C H A P T E R 1 — I N T RODUCT ION Chapter 1: 1.1). EC O N O M I C A N D S E CT OR WORK Nitrous oxide from soils. climate change may reduce crop yields by 10 to 20 percent (Jones and Thornton 2009). enhancing the resilience of natural ecosystems. where possible. fuel.

ƒ maintain suitable biotic habitat. ƒ promote and sustain root growth. the fundamental cause of declining crop productivity in developing countries. and ƒ respond to management and resist degradation. and reduce agriculture’s contribution to climate change by reducing GHG emissions and increasing soil carbon storage. and release water both for plants and for surface and groundwater recharge. defined as the ability of soils to function in natural and managed ecosystems. The overall increase in grain productivity in Africa. while another 28 percent came from the conversion of degraded forests (Gibbs et al. Asia. 2010. reducing emissions.2). hold. Climatesmart agriculture (CSA) seeks to increase productivity in an environmentally and socially sustainable way. and hydrosphere.CH A PTER 1 — INTR OD UC TION 2 FIGURE 1. figure 1. It also provides the biogeochemical linkage between other major carbon reservoirs. agricultural land in the tropics came at the expense of intact forests. and enhancing resilience to climate change call for alternative approaches to practicing agriculture. CARBON SEQUESTRATION IN AGRICULTURAL SOILS . and Latin America due to such increase in soil organic carbon is estimated at 24 to 40 million tons per year (table 1. 1980–2000 100% 90% 80% 70% Water 60% Plantations 50% Shrubs 40% Disturbed forests 30% Intact forests 20% 10% As ia ca h ut So tA W es Af st fri ric a ica h ut So Ea Am st Ea hut So er As ia ca fri lA ra nt Ce lA ra nt Ce Pa n -Tr m op er ics ica 0% Source: Redrawn from Gibbs et al. namely the biosphere. One of the key elements of CSA is sustainable land management (SLM) involving the implementation of land-use systems and management practices that enable humans to maximize the economic and social benefits from land while maintaining or enhancing the ecosystem services from land resources. Increasing soil organic carbon can reverse soil fertility deterioration.2).2: Proportion of Agricultural Land Derived From Different Land Covers in the Tropics. Projected increases in demand for food and bioenergy by 2050 may further increase pressure on forests in the tropics with profound implications for an increase in GHG emissions. strengthen farmers’ resilience to climate change. growth in agricultural emissions under a business-as-usual world with a near doubling in food production would perpetuate climate change. Soil carbon influences five major functions of the soil (Larson and Pierce 1991). 1. (2010). ƒ accept. hold. It supports all the terrestrial ecosystems that cycle much of the atmospheric and terrestrial carbon. Soil carbon is held within the soil. Soil is central to most SLM technologies because it is the basic resource for land use.2 CARBON BENEFITS THROUGH CLIMATE-SMART AGRICULTURE The triple imperatives of increasing productivity. Soil carbon has a strong correlation with soil quality. primarily in association with its organic constituent. Even if emissions in all other sectors were eliminated by 2050. Table 1. namely the ability to ƒ accept.1 indicates the potential increase in crop yields from increasing the soil organic carbon pool in the root zone by 1 ton C/ha/yr through SLM technologies. atmosphere. and release nutrients.

5–23.9 0. EC O N O M I C A N D S E CT OR WORK 0.2 4.9–4.5–5.6–5.01 1. TABLE 1. and nitrous oxide).2: Estimated Increase in Grain Crop Production from Land Management Technologies That Sequester Soil Carbon (Million Tons/Year) CROP AFRICA ASIA LATIN AMERICA TOTAL Maize 0. Zero tolerance for soil erosion is indispensable for soil carbon conservation.1–8.2 4. Many natural land systems such as native forests. draining of wetlands (carbon dioxide and nitrous oxide). Emission of these gases from agricultural ecosystems is increased through subsistence agricultural practices that do not invest in soil quality improvement practices such as erosion control.01–0. Soil carbon sequestration is the process by which atmospheric carbon dioxide is taken up by plants through photosynthesis and stored as carbon in biomass and soils.7–1.1–0. It entails replenishing lost carbon and adding new carbon (organic inputs) beyond original levels. deforestation (carbon dioxide. Historically.0–1.7 3. water management.4 Sorghum 1.4–0.C H A P T E R 1 — I N T RODUCT ION 3 Furthermore. improving soil biodiversity.1: Improvement in Crop Yields per Ton of Carbon in the Root Zone CROP POTENTIAL YIELD INCREASE (kg/ha) Maize 200–400 Wheat 20–70 Soybean 20–30 Cowpea 5–10 Rice 10–50 Millet 50–60 Soil carbon also enhances resilience to climate variability and change by improving soil structure and stability. reducing soil erosion.6 3. Conserving this terrestrial carbon pool accumulated over millennia should be a major priority. reducing the impacts of drought. namely carbon conservation.3–0. and application of fertilizers and other amendments (World Bank 2010).3–0.4 2.0 Millet 0.2 0.0 0. improving aeration and water-holding capacity.1 23.9 9.7 0.4–0.2 1.9 0. For instance. new technologies such as deeper-rooted crops and pasture grasses can enhance original soil carbon up to a given equilibrium.7–7.6–10.5 . and wetlands have relatively high carbon stocks.5–0. and increasing nutrient use efficiency. and uncontrolled grazing (carbon dioxide and nitrous oxide). Removal of the vegetation cover aggravates losses by soil erosion and increases the rate of decomposition due to changes in soil moisture and temperature regimes.4–16. as it offers the greatest least-cost opportunity for climate mitigation and ecosystem resilience. Sustainable land management practices are an alternative to several conventional agricultural practices that lead to emissions of GHG from the soil to the atmosphere. plowing and soil disturbance (carbon dioxide). and nitrous oxide).6–1. can be recaptured through sustainable land management practices.6–39. intercropping food crops with trees.4 Wheat 0. the removal of crop residues and cattle manure for fuel leads creates a negative carbon budget and must be prevented. farmers can increase crop yields.5–6. and carbon sequestration.1–6. methane. limit GHG concentrations in the atmosphere.3–1.8–1.7–2. reduce rural poverty. Because soil organic matter is concentrated on the soil surface. methane. grasslands.2–0.3 4.1–0. The use of crop residues as mulch.8–1. These conventional practices include biomass burning (that releases carbon dioxide.4–5.2–0.6 3.7 6.3 4. Source: Lal (2011). and reduce the impact of climate change on agricultural ecosystems.4 Soybean Total Source: Lal (2003).7 0. reduced emissions. agricultural soils have lost more than 50 Gt (1 Gt = 1 billion tons) of carbon.8 Beans 0.03 0. Sustainable land management provides carbon benefits through three key processes. however.0–1.7 13. Agricultural soils should be prevented from being washed to streams and rivers where the relatively stable soil C pools are rapidly oxidized to carbon dioxide (Lal 2003).9 Rice 0. and integrated nutrient and water management also sequester carbon in the soil.6 1. Some of this carbon. TABLE 1. By adopting improved land management practices to increase soil carbon.5 0. accelerated soil erosion leads to progressive depletion of soil carbon.5 0.8 0.02–0.4–0.

K. Ruesch. Chapter 3 reports the increase in soil carbon for selected sustainable land management practices in Africa. F. R. Furthermore... A. 12 (2): 175–203. Ogle. 2008. and Pierce. IBSRAM Proceedings No. Foley. “Greenhouse Gas Mitigation in Agriculture. Land Use.” In Evaluation for Sustainable Land Management in the Developing World. The report will provide a broad perspective to natural resource managers and other professionals involved in scaling up CSA. K.. Bredit. Myers.” Philosophical Tranactions of the Royal Society B 365: 2973–2989. R. 2003. and Thornton. F. N... P. Achard.. M. A. Guo. Land-Use Change. and Forestry. Latham.” Proceedings of the National Academy of Sciences 107 (26): 12052–12057. (2005). A. While there are many studies on soil carbon sequestration... J. Thailand: International Board for Research and Management. REFERENCES Burney. Bangkok. Dumanski. E. Davis.. Robert et al. “Croppers to Livestock Keepers: Livelihood Transitions to 2050 in Africa Due to Climate Change. and Lobell. Asia.” Proceedings of the National Academy of Sciences 107 (38): 16732–16737. Intergovernmental Panel on Climate Change. E. CARBON SEQUESTRATION IN AGRICULTURAL SOILS .. “Greenhouse Gas Mitigation by Agricultural Intensification. Chapter 2 provides a brief review of soil organic carbon dynamics and the methods for soil carbon assessment. “Soil Erosion and the Global Carbon Budget. M. J. agro-ecosystems resilience. while Chapter 5 concludes with the benefits and costs of adopting carbon sequestering practices and a review of evolving funding mechanisms to support climatesmart agriculture in developing countries. P. J. 2010. Environment Department. R. H. “Implications of Climate Change for Agricultural Productivity in the Early Twenty-First Century. and Wiltshire. L. 2009. Larson.. the ecosystem simulation modeling technique was used to predict future carbon storage in global cropland soils. K. Gornall. D. D.. “Agricultural Management Impacts on Soil Organic Carbon Storage Under Moist and Dry Climatic Conditions of Temperate and Tropical Regions.” Biogeochemistry 72: 87–121. “Soil Carbon Stocks and Land-Use Change: A Meta Analysis. Cambridge University Press. but the sequestration rates in these papers are highly variable and not specific to local conditions.1098/rstb. Cai. 2: Technical Papers. Chapter 4 reports the estimates from ecosystem simulation. “Pathways of Agricultural Expansion Across the Tropics: Implications for Forest Resources.” Philosophical Transactions of the Royal Society B 363: 789–813. Pushparajah. Clark. S. Martino. “Sequestering Carbon in Soils of Agroecosystems.” Global Change Biology 8: 345–360.” Environmental Science and Policy 12: 427–437. Climate Change 2007: Synthesis Report—Summary for Policymakers. J. P. B. et al. Intercontinental Panel on Climate Change (IPCC). Major exceptions are Guo and Gifford (2002) and Ogle et al.” Food Policy 36: S33–S39. 2010. The remainder of the report is organized as follows. J.” Environment International 29: 437–450. Cambridge. and Latin America. Last. Fourth Assessment Report. 2005. “Conservation and Enhancement of Soil Quality. Jones.. W. Lal. This is one important element in decision-making for sustainable agricultural intensification. Vol. Smith. and Holmgren. and Latin America. P. J.. 2 Gibbs.0158. Ramankutty. marginal abatement cost curves and trade-off graphs were used to assess the cost-effectiveness of the technologies in carbon sequestration. ed. there is no single unifying volume that synthesizes knowledge on the impact of different land management practices on soil carbon sequestration rates across the world. S. S. Camp. Burke. and comprehensive assessments of greenhouse mitigation potentials of SLM practices. and Pasutian. 2000.2 A meta-analysis was carried out to provide soil carbon sequestration rates in Africa. 2010.. World Bank. ed.. 1991. Betts. F. Watson.3 OBJECTIVES AND SCOPE OF THE REPORT The purpose of this report is to improve the knowledge base for facilitating investments in land management technologies that sequester soil organic carbon.2010. 2002. A. Sustainable Land Management for Mitigation of and Adaptation to Climate Change. Asia.. and Gifford.4 CH A PTER 1 — INTR OD UC TION 1... R. Willett. Lal. J.. 2011. Z.. doi:10. R. J. The chapter concludes with brief information on carbon assessment in The World Bank’s sustainable land management projects portfolio. 2007.. and R. 2010. E.

aspx. while croplands occupy about 11 percent (table 2. IGBP-DIS. 2008. Of the estimated over 150 million km2 of terrestrial ecosystems area. which is slightly lower than 60 percent they removed some 50 years ago (Global Carbon Project 2009). The efficiency of oceans and lands as carbon dioxide sinks has declined over the years. 2000. Emissions from land-use change are about 1. population growth. EC O N O M I C A N D S E CT OR WORK 5 . The two most important anthropogenic processes responsible for the release of carbon dioxide into the atmosphere are burning of fossil fuels (coal. and natural gas) and land use (table 2.no/publications/rr/natural-fix/page/3724.1 SOIL ORGANIC CARBON DYNAMICS AND ASSESSMENT METHODS SOIL ORGANIC CARBON DYNAMICS Different ecosystem types store different amounts of carbon depending on their species compositions.grida. and international trade. Currently. soil types. Savannahs and grasslands both cover about 23 percent. natural sinks remove an average of 55 percent of all anthropogenic carbon dioxide emissions.C H A P T E R 2 — S O I L ORGANIC CARBON DYNAMICS A ND A SS ES S MENT METH OD S Chapter 2: 2. covering an area of less than 10 million km2. climate. Rapidly growing emissions are outpacing the growth in natural sinks. and other biophysical features (figure 2. vegetation carbon stocks range from 3 Gt for croplands to 212 Gt for tropical forests.5 Gt C per year. policy and institutional failures. Soils generally hold more carbon than vegetation across biomes and account for 81 percent of terrestrial carbon stock at the global level. and oceans. Source: UNEP/GRID.1). soils. The underlying driving factors of tropical deforestation are highly interconnected and include poverty.2). FIGURE 2. The global carbon cycle describes the transfer of carbon in the earth’s atmosphere. The tundra biome.1). while soil carbon stocks range from 100 Gt for temperate forests to 471 Gt for boreal forests. http://www. largely determined by tropical deforestation that exacerbates soil erosion and organic matter decomposition. Among the biomes.1: Carbon Stocks in Biomass and Soils Carbon storage in terrestrial ecosystems (Tonnes per ha) 0 to 10 10 to 20 20 to 50 50 to 100 100 to 150 150 to 200 200 to 300 300 to 400 400 to 500 More than 500 Source: Ruesch and Gibbs. vegetation. urban expansion. has the highest density of carbon storage. and the attendant demand for natural resources. forests account for more than 40 million km2 (about 28 percent). oil. relief.

477 19 81 100 Proportion (%) Source: Based on Watson et al. and root die-off. Breeding crop plants with deeper and bushy root ecosystems could simultaneously sequester more carbon. Soils are critically important in determining global carbon cycle dynamics because they serve as the link between the atmosphere.9 −2.2: Global Carbon Budget (Gt C) SOURCE 1980s 1990s 2000–2008 Atmospheric increase 3.9 −1.2 ± 0.7 131 Croplands Total 16 151.3).4 7.3 6.8 240 3 2.5 6 4.7 121 95. These compounds originate from the photosynthetic activities of plants.3 559 Tropical savannas 22.011 2.4 ± 0. energy for biological processes.7 ± 1.0 264 80.0 191 96.2 466 2.5 8 4. Crop residues are readily broken down and serve as substrates to soil microorganisms. vegetation.3 225 93. The elemental and inorganic forms of soil carbon primarily result from mineral weathering and are less responsive to land management than soil organic carbon (table 2.7 471 84.4 ± 0. the soil carbon pool (also referred to as the pedologic pool) is estimated at 2.6 CHAPTER 2 — S OIL OR GA NIC CA R B ON D YNA MIC S A ND A SS ES S MENT M ETH OD S TABLE 2.0 295 97.550 Gt. improve water and nutrient retention.4 −2.7 −2.7 88 15. plants reduce carbon from its oxidized form to organic forms (net primary productivity.5 15 6.5 216 50. Out of this.6 ± 0.3 ± 0. release of sap exudates from plant roots into the soil.4 ± 1.1: Carbon Stocks in Vegetation and Top 1 Meter of Soils of World Biomes BIOMES Tropical forests CARBON STOCKS (Gt C) AND PROPORTION IN THE ECOSYSTEM (%) AREA (MILLION km2) VEGETATION PROPORTION (%) SOILS PROPORTION (%) TOTAL 17. Different fractions or soil organic carbon pools have different functions within the soil system.7 ± 1.5 9 3.2 ± 0. microbial organisms.7 1. Particulate organic carbon is broken down relatively quickly but more slowly than other crop residues and is important for soil structure. Through photosynthesis.5 Net land-to-atmosphere flux −0.4 ± 0.and below-ground decomposition of materials. The soil carbon pool is more than three times the size of the atmospheric pool (760 Gt) and about 4. and oceans. and increase crop yields (Kell 2011).0 Sources: IPCC (2007) and the Global Carbon Project (2009).8 ± 0. TABLE 2.8 −2.5 times the size of the biotic pool (560 Gt). NPP) useful for growth and energy storage. Globally.5 66 20. Soil organic carbon is a complex mixture of organic compounds composed of decomposing plant tissue. while the soil inorganic carbon and elemental pools make up the remaining 950 Gt (Batjes 1996).6 −1. and provision of nutrients for plants. and carbon bound to soil minerals.1 Fossil fuel emissions 5.0 1.5 428 Temperate forests 10.7 −1.0 330 Temperate grasslands 12. the soil organic carbon pool comprises 1.0 ± 0.6 ± 0.500 Gt up to 2 meters deep.0 199 Tundra 9.6 212 49.1 100 62.3 ± 0.7 Partitioned as: Land-use change flux Residual land sink 1.1 4.3 ± 0.3 ± 0.0 304 Deserts 45.2 ± 0. improve soil structure.1 ± 0. A more stable fraction.9 159 Boreal forests 13.3 128 97.4 59 37. Over time.3 127 Wetlands 3.3 Net ocean-to-atmosphere flux −1.1 3. the C fixed in the atmosphere becomes soil carbon through the process of above. CARBON SEQUESTRATION IN AGRICULTURAL SOILS . (2000) and Ravindranath and Ostwald (2008).

Organic Plant and animal materials at various stages of decomposition ranging from crop residues with size of 2 mm or more Plant debris. highly decomposed materials less than 0. insoluble form that is not subject to further decomposition. histosols.7 C H A P T E R 2 — S O I L ORGANIC CARBON DYNAMICS A ND A SS ES S MENT METH OD S TABLE 2.g.1). water retention.g. and oxisols. siderite (Fe CO3) Agricultural inputs such as liming can also introduce calcite and dolomite into the soil.. to some extent.05 and 2 mm humus. Some very stable humus complexes can remain in the soil for centuries or millennia. and box 2. usually as carbonates—that is. inceptisols. ultisols. table 2. Active humus is an excellent source of plant nutrients (nitrates and phosphates).2. also referred to as particulate organic carbon.000 Soil orders Alfisols Entisols Inceptisols Spodosols Rocky land Andisols Gelisols Mollisols Ultisols Shifting sand Aridisols Histosols Oxisols Vertisols Ice/glacier Source: United States Department of Agriculture. graphite. EC O N O M I C A N D S E CT OR WORK . the largest amount of soil organic carbon is found in oxisols. charcoal. calcite. the highly stable. In the tropics. CaCO3 dolomite.2: Global Soil Regions Robinson projection scale 1:130. alfisols. entisols. and tilth. can be classified into two depending on the level of decomposability: The first is active humus that is still subject to further decomposition.000. humus. and the other is passive humus (or recalcitrant carbon). with size between 0..05 mm that are dominated by molecules attached to soil minerals Source: Synthesized from Schumacher (2002).3: Forms of Carbon in the Soil FORMS SOURCES Elemental Geologic materials (e. At the global level. while passive humus is important for soil physical structure. CaMg(CO3)2 and. and soot) Dispersion of these carbon forms during mining Inorganic Geologic or soil parent materials. graphite and coal) Incomplete combustion of organic materials (e.4. and inceptisols (figure 2. the soil organic carbon pool is concentrated in five major soil orders: histosols. FIGURE 2.

box 2. residue removal. Such factors include soil texture and clay mineralogy.16 to 0.580 352 22.2). corresponding to carbon emissions of 0. The potential carbon sequestration is controlled primarily by pedological factors that set the physico-chemical maximum limit to storage of carbon in the soil. biomass burning.1).9 30 5. However.1 Gt carbon per year (table 2. Land management practices that increase carbon input through increasing NPP tend to increase the attainable level to nearer the potential level.6 100 19.6 71 4.330 8. The annual soil losses in Africa.2 Gt of C emitted to the atmosphere each year. tillage operations.7 Entisols 14.5 110 7 9.644 5.9 1.7 18 1.1 6. The attainable carbon sequestration is set by factors that limit the input of carbon to the soil system.8 Vertisols 3. The degree of loss is higher in soils that are susceptible to accelerated erosion and other soil degradation processes.5). The amount changes over time depending on photosynthetic C added and the rate of its decay.4 Ultisols 11. Climate has both direct and indirect effects on attainable sequestration.2 60 11.743 23.1 1.552 1.9 Mollisols 5. and drainage of peat lands) is between 0. bulk density.358 2.9 78 4. NPP—the rate of photosynthesis minus autotrophic respiration—is the major factor influencing attainable sequestration and is modified by above-ground versus below-ground allocation. Under undisturbed natural conditions.772 8.4 11. soil erosion accounts for up to 1.4 29 5. and proportion of coarse fragments (figure 2. The actual carbon sequestration is determined by land management factors that reduce carbon storage such as The current rate of carbon loss due to land-use change (deforestation) and related land change processes (erosion.283 13.2 2. Theoretically.480 4.1 72 4.44 Gt per year (table 2.3). the potential soil carbon sequestration capacity is equivalent to the cumulative historical carbon loss.6 11.4: Soil Carbon Pool up to 1-M Deep for Soil Orders of the World’s Ice-Free Land Surface GLOBAL LAND AREA SOIL ORDER EXTENT (1000 km2) PROPORTION (%) SOIL ORGANIC CARBON POOL (Gt) TROPICAL LAND AREA PROPORTION (%) EXTENT (1000 km2) PROPORTION (%) SOIL ORGANIC CARBON POOL (Gt) PROPORTION (%) Alfisols 18.256 6.4 19 1.6 19 3.9 Andisols 2.669 100 506 100 Source: Eswaran et al.5 2 0.7 and 2. This is more than 57 percent CARBON SEQUESTRATION IN AGRICULTURAL SOILS .7 2 0.4 Oxisols Spodosols Total 135. and drainage.8 Histosols 1.565 9.3 16 100 1.3 Aridisols 31.018 18. and Asia are estimated at 39 to 74 Gt.5 127 8.512 23.4 47 9. South America. organic matter decomposition.287 2.2 Others 7. This is more than 50 percent of the carbon absorbed by land.411 12.2).921 11 148 9.2 119 23.4 3. The conversion of natural vegetation to agricultural ecosystems leads to a depletion of the soil organic carbon pool by as much as 60 percent in the temperate regions and by 75 percent or more in the tropics (box 2. (1993).5 40 0. erosion. depth.4 105 6.745 357 22. The soil organic carbon pool represents a dynamic balance between gains and losses. aeration.189 4. The decomposition rate increases with temperature but decreases with increasingly anaerobic conditions.5 4.215 1.6 234 0.7 119 7.683 3. residue removal.7 286 0.576 100 49. tillage.7 9. and leaching. only 50 to 66 percent of this capacity is attainable through the adoption of sustainable land management practices (Lal 2004.1 2 0.8 Inceptisols 21.2 85 16.8 CHAPTER 2 — S OIL OR GA NIC CA R B ON D YNA MIC S A ND A SS ES S MENT M ETH OD S TABLE 2.4 11 2. Soil erosion is the major land degradation process that emits soil carbon. excessive fertilizers.117 18. Globally. inputs of carbon from litter fall and root biomass are cycled by output through erosion.878 3.3 4.

The paucity of vegetation also leads to low organic matter content. Each year. droughts. Most histosols are saturated all the year round. relatively high organic matter. mollisols are grassland soils with dark-colored surface horizons. bogs. a small change in soil respiration can significantly alter the balance of atmospheric carbon dioxide concentration compared to soil carbon stores. Source: Modified from United States Department of Agriculture. mucks. or moors. Soil respiration is regulated by several factors including temperature. spodosols have developed from weathering processes that strip organic matter and iron and aluminum oxides from the surface to the subsoil. making most gelisols black or dark brown in color. some soils of the riverine floodplains of the Ganges and Brahmaputra Rivers in Bangladesh and India. Spodosols: Commonly occurring in areas of coarse-textured deposits of humid regions. Thus. Ultisols: Formed from fairly intense weathering and leaching that results in clay accumulation at the subsoil.1: Brief Description of Soil Orders Alfisols: Formed primarily under forest or mixed vegetative cover. or sand dunes. oxisols are highly weathered soils of tropical and subtropical regions. They are commonly called peats. They occur in many environments such as on steep slopes. and the floodplains of Southeast Asia. Vertisols: Dominated by high content of swelling and shrinking clay minerals.C H A P T E R 2 — S O I L ORGANIC CARBON DYNAMICS A ND A SS ES S MENT METH OD S BOX 2. the flux of microbially and plant-respired carbon dioxide (CO2) from the soil surface EC O N O M I C A N D S E CT OR WORK to the atmosphere. They have moderately low capacity to retain fertilizer and soil amendments. the terrestrial carbon pool assimilates 120 Gt C from the atmosphere in the form of gross primary productivity (or photosynthesis). They are found on stable landscapes. andisols result from weathering processes that generate minerals with little orderly crystalline structure (volcanic glass) and usually have high nutrientand water-holding capacity. It is about 60 times the annual contribution of land-use change and about 11 times that of fossil fuel to atmospheric emissions. Mollisols: Formed under moderate to pronounced seasonal moisture deficits. Entisols: Occurring in areas of recently deposited parent materials or areas where erosion or deposition rates exceed the rate of soil development. and high base saturation. 9 . the lack of moisture markedly restricts the intensity of weathering and development of aridisols. vertisols typically form from highly basic rocks in climates that are seasonally humid or subject to erratic floods. inceptisols are formed on recent geomorphic surfaces in semi-arid to humid environments. but they are difficult to till. Oxisols: Dominated by low activity minerals. Spodosols tend to be acidic and are inherently infertile. estimated at 75 to 100 Gt C per year is the next largest terrestrial carbon flux (Raich and Potter 1995). histosols have a high content of organic matter and no permafrost. Gelisols are not highly fertile because nutrients are very easily leached above the permafrost. Vertisols tend to be high in natural fertility. ultisols are typically acidic with most nutrients concentrated in the topsoil. Gelisols: Found mostly in very cold areas under the influence of glaciation. and low capacity to retain fertilizer and soil amendments. Histosols: Formed in decomposed organic materials that accumulate faster than they decay. entisols are characterized with little or no horizon development. Included in this category are partially developed soils of the Sahel region of West Africa. High amounts of soil organic matter accumulate in the upper layer. gelisols are characterized by permafrost within 2 m of the soil surface. Soil respiration. of the emission through land-use change and underscores the need for carbon conservation through zero tolerance for soil erosion. or impeded drainage. alfisols result from weathering processes that leach clay minerals from the surface to the subhorizon. Inceptisols: Exhibiting modest soil weathering and horizon development. have low natural fertility. Aridisols: Formed under arid climates. flood plains. Andisols: Common in cool areas with moderate to high precipitations.

16–0. Variations in temperature are significantly and positively correlated with changes in global soil respiration (Bond-Lamberty and Thompson 2010).2–0.8–1.1 0.6 0.30–0.2 0.16 Europe 13.44 South America 39.5–2.1 0. about 10 CARBON SEQUESTRATION IN AGRICULTURAL SOILS .0–6. the global soil respiration reached roughly 98 Gt. nitrogen content.24 Asia 74.8–1. In 2008.04 201. moisture.2 0.1 4.0 0.2 0.04–0.2 0.5: Estimate of Erosion-Induced Carbon Emission CONTINENT GROSS EROSION (X 109 Mg/YEAR) SOIL CARBON DISPLACED BY EROSION (2 TO 3 PERCENT OF SEDIMENT. Gt C/YEAR) Africa 38. Gt C/YEAR) EMISSION (20 PERCENT OF DISPLACED SOIL CARBON.3: Factors Affecting Soil Carbon Sequestration Potential Defining factors: – Mineralogy/content – Depth – Stoniness – Bulk density – Aeration Attainable Limiting factors: – NPP and allocation – Climate (direct) – Climate (via NPP) Reducing factors: – Erosion – Tillage – Residue removal – Disrupted biology – Drainage SOC-increasing measures Actual SOC-protecting measures SOC level (t1/2 ≥ 10 years) ton ha–1 Source: Redrawn from Ingram and Fernandes (2001).8 0. TABLE 2.1–0.10 CHAPTER 2 — S OIL OR GA NIC CA R B ON D YNA MIC S A ND A SS ES S MENT M ETH OD S carbon sequestration situation FIGURE 2.8–1.02–0.6–0.24 North America 28. Higher temperatures trigger microbes to speed up their consumption of plant residues and other organic matter. Climate change is positively correlated with increasing rate of soil respiration.2 Oceania Total Source: Adapted from Lal (2003).12–0. vegetation type.4 0.08 7.16–0.9 0. and level of aeration of the soil.0 1.4 0.

3 t ha−1 between 1960 and 1970 (see figure below). sustainable land management practices can accumulate soil organic carbon. green compost.. rubber. During the Dutch colonial period. improve soil quality. By the 1990s. Y. and McBrateney A. Sulaeman. As a result. and enhance ecosystem services supply from the soil. between 1960 and 1970. B. decline in soil carbon stock was primarily due to conversion of forests to cropland. most land development was for plantations such as tea. and until the early 1960s. Some soil scientists have recently used legacy soil survey data to capture the long-term trend of soil organic carbon in Java in Indonesia (Minasny et al. 2010. 2010). increased soil carbon sequestration. reverse chronic soil degradation. Global Change Biology 17:1917–1924. and coffee. and animal manure application were mostly responsible for the increase in soil organic carbon stock. However. With an estimated population density of 1. An analysis over the period from 1930 to 2010 revealed that human activities are more important than environmental factors in explaining soil organic carbon trend. Further intensification has resulted in improved environmental awareness. soil organic carbon markedly declined by 62 percent of its natural condition. EC O N O M I C A N D S E CT OR WORK 11 . Indonesia faced a serious problem of food scarcity. throughout its independence years. Between 1930 and 1950.2: Sustainable Land Management Practices Reverse Soil Carbon Loss in Java Research in the tropics has demonstrated the decline of soil organic carbon by as much as 60 percent after conversion of forest to cropland. 25 20 t ha–1 15 10 5 0 1930–1940 1940–1950 1950–1960 1960–1970 1970–1980 1980–1990 1990–2000 2000–2010 Source: Minasny. soil organic carbon stock had risen to about 11 t ha−1 as there was also a large interest in organic farming in Java.026 persons km−2.C H A P T E R 2 — S O I L ORGANIC CARBON DYNAMICS A ND A SS ES S MENT METH OD S BOX 2. The Green Revolution of the 1960s saw Java producing close to two-thirds of the country’s rice. Is soil carbon disappearing? The dynamics of soil organic carbon in Java. This huge drop was mostly due to the high conversion of forests and natural vegetation into plantations and subsequently to food crops.4 t ha−1 between 1930 and 1940 to 7. The median soil organic carbon stock in the topsoil dropped from 20.. Java is undoubtedly the most densely populated and the most intensively cultivated island in Indonesia. The increased biomass and the return of crop residues. soil organic C has increased slightly as a result of the government extension program to disseminate new agricultural production knowledge among farmers. Since the late 1960s. including the use of highyielding varieties and chemical inputs.B. and increased resilience of the agricultural system. increased likelihood of adoption of sustainable land management practices. From the Japanese occupation in 1942.

When other factors are at optimum. Furthermore. Carbon assessment for land management projects not principally designed for climate change mitigation is carried out for a number of reasons: ƒ The need to assess the carbon footprint of the operational work of funding agencies (see section 2. supporting. radar. and 2. dead wood. Signatory parties of the UN Framework Convention on Climate Change (UNFCCC) are required to prepare national GHG inventories on a periodic basis and report them to the body. and water management can optimize soil respiration in addition to improving soil carbon. and provisioning ecosystem services. use of cover crops (green manure). Soil carbon assessment in different parts of the world requires methods that are appropriate to the circumstances. for carbon projects. Mitigation projects involve estimation of verifiable changes in carbon stocks over a given period in the defined project area and require methods for estimating carbon stocks and changes for the baseline scenario (without the project) and the project. excessive respiration.6. crop rotations.12 CHAPTER 2 — S OIL OR GA NIC CA R B ON D YNA MIC S A ND A SS ES S MENT M ETH OD S times more carbon than humans release into the atmosphere each year. and litter—and the soil organic carbon pool. The key differences for carbon assessment for the two types of projects are summarized in table 2. application of manure. credible CARBON SEQUESTRATION IN AGRICULTURAL SOILS . but effort is required to ensure that the methods are comparable. measurement techniques. Soil respiration increased 0. Estimating the area under a given land-use category in a given year and the area under each category subjected to land-use change 2. Use of optical. 2. conservation tillage. A rise in temperature by 2°C is estimated to release an additional 10 Gt C per year to the atmosphere through soil respiration (Friedlingstein et al. while non-Annex I or developing countries only need to report every 3 to 5 years. Biome averages involving the estimation of average forest carbon stocks for broad forest categories based on a variety of input data sources. Estimating the stocks of carbon in each pool at the beginning and end of the period to calculate net emissions or removal (stock difference approach) 3.3 TECHNIQUES OF SOIL CARBON ASSESSMENT Methods to assess above-ground biomass are more advanced than for soil carbon. ƒ Changes in soil carbon over the lifetime of a project are an indicator of the success of SLM intervention. 2003). Forest inventory that relates tree diameters or volume to forest carbon stocks using allometric relationships. The assessment covers four biomass pools—above ground.4). 2. Excessive application of large amounts of nitrogenous fertilizer can markedly increase root biomass and stimulate soil respiration rates. The key steps involved are as follows: Typically. and soil organic matter decomposition. Carbon assessment for land management projects can be either purposely for climate mitigation or for nonclimate mitigation.2 CARBON ASSESSMENT FOR LAND MANAGEMENT PROJECTS Carbon assessment entails the estimation of stocks and fluxes of carbon from different land-use systems in a given area over a period of time. and models tailored to their particular circumstances. though this is hardly a prime objective. Estimating the gain in carbon stock for each pool due to accumulation or losses and calculating the difference between gains and losses as net emissions or removal (a gain-loss approach). below ground. 3. Many different methods have been tested in a number of countries. 1. or laser remote-sensing data integrated with allometry and ground measurements. different countries adapt the Intergovernmental Panel on Climate Change (IPCC) guideline for national GHG by using sampling methods. ƒ Interest in benefiting from carbon finance. Annex I or industrialized countries are required to estimate and report emissions and removals annually. 2007): 1. ƒ Changes in soil carbon stocks can help track changes in regulating. Conventional tillage leads to the destruction of soil aggregates. The assessment can be undertaken either at national or project level. Tillage operations can significantly affect soil respiration. leading to reduced crop production and decreased resilience of the soil ecosystem. The three major methods for above-ground carbon assessment include the following (Gibbs et al. use of deep-rooted crops.1 Gt C per year between 1989 and 2008.

though more precise and accurate. biodiversity conservation. well-defined plan is required for monitoring of local environmental and socioeconomic impacts Project review and appraisal Baseline and project scenario carbon monitoring methods are critical Monitoring plan for local environmental and socioeconomic benefits is important Implementation Activities aimed at maximizing carbon benefits. b Carbon assessment methodologies are the blueprints to design. and operate carbon projects. and biodiversity need to be clearly identified. use of in situ analytical methods. watershed protection. (2008) observed that organic layer carbon measurements cost 520 per plot if 10 samples are analyzed. Makipaa et al. and livelihood improvement Monitoring and evaluation Approved methodologiesb are crucial. and sampling design requirements and associated levels of bias or uncertainty.7 has unique constraints related to costs. whether for national or regional accounting or for carbon offset project. crop yields. verify. A comparison of these techniques is provided in table 2. inadequacies. and the use of biogeochemical models. One round of measurement was estimated to cost about 4 million. two measurements for a minimum of 3. pooled sampling. Most of the in situ techniques are still in their infancy. The exception is infrared spectroscopy currently being 13 . corresponding to 8 percent of the value of the annual sequestration of about 3 million tCO2 of Finland’s upland forest soils. CROPLAND MANAGEMENT) Primary focus: carbon mitigation and carbon credits—global environmental benefit Primary focus: forest and biodiversity conservation. Also. Field sampling is technically challenging. Strategies to reduce the cost of soil carbon monitoring include lengthening the sampling interval. Soil carbon assessment methods can be broadly classified into direct and indirect methods depending on whether carbon content in soil samples is directly measured or inferred through a proxy variable (table 2. The precision obtained with such sampling corresponds to detection of soil carbon change greater than 860 g C m−2. soil fertility. The direct method.6: Comparison of Carbon Assessment for Carbon Mitigation and Non-Carbon-Mitigation Projects PROJECT PHASE Conceptualization Proposal development CARBON MITIGATION PROJECTS NONCARBON-MITIGATION PROJECTS (SUSTAINABLE LAND MANAGEMENT INCLUDING FOREST. Each of the methods depicted in table 2. but it can be addressed with appropriate design that accounts for soil spatial variation.7). Each context will require a differing degree of granularity and measurement set to assess uncertainty in the estimates. Additionality must be demonstrated Project-specific methodology is used All the relevant carbon pools must be considered Large transaction cost likely for carbon inventory and monitoring Additionality of local environmental and socioeconomic benefits are critical Soil carbon critical for land development projects due to effects on agricultural sustainability Moderate transaction cost for monitoring Source: Modified from Ravindranath and Ostwald (2008).000 plots are needed to detect an expected change of 11 g C m−2 yr−1 in the organic layer of upland forest soils at 10-year sampling intervals. a Project boundary refers to the physical boundary of the land area delineated either with a geographical information system or a global positioning system and the greenhouse gas boundary that includes all fluxes of all gases affected by project activity. and cost-effectiveness over conventional ex situ methods. increasing the efficiency of sampling through stratification. GRASSLAND.8. and cost-effective techniques of monitoring changes in soil carbon are required. geographic scope. and livelihoods enhancement Secondary focus: soil and biodiversity conservation Cobenefits: carbon mitigation is implicit though often not mentioned in proposal Clear historical records of the past vegetation and soil carbon status are required Historical vegetation status not so critical to project eligibility Project boundarya impacted by project activities needs clear definition Project boundary needed for estimating environmental and socioeconomic benefits restricted to project area Estimation of baseline carbon stocks is crucial as well as rigorous plan for monitoring carbon stock changes Baseline economic benefits.C H A P T E R 2 — S O I L ORGANIC CARBON DYNAMICS A ND A SS ES S MENT METH OD S TABLE 2. They document the protocol for quantifying carbon emissions and removals and include guidelines for identifying baseline scenario and assessing additionality in all carbon pools relevant to the project. At the national level. is quite laborious and very expensive. followed by other cobenefits Activities are aimed at maximizing biomass production. Most assessments typically involve a combination of these techniques. The degree and nature of sampling depend on the carbon assessment objective. EC O N O M I C A N D S E CT OR WORK In Finland. Several in situ soil carbon analytical methods are being developed with the objective of offering increased accuracy. precision. The most established type of direct soil carbon assessment entails collecting soil samples in the field and analyzing them in the laboratory by combustion techniques.

flux tower measurements Biogeochemical/ecosystem simulation modeling to understand below-ground biological processes.8: Characteristics of Emerging In Situ Methods of Soil Carbon Analytical Techniques DIRECT METHOD TYPE OF RADIATION MEASURED PROCESS PENETRATION DEPTH (CM) Mid-infrared spectroscopy Molecular/diffuse reflectance Infrared 1 Near-infrared spectroscopy Molecular/diffuse reflectance Near infrared 0. TABLE 2. capable of spectrally resolving several elements apart from carbon Interference with iron compounds around 248 nm wavelength. Eddy covariance.  RothC  Century  DNDC  PROCOMAP  CO2FIX 3.7: Direct and Indirect Methods of Soil Carbon Assessment DIRECT METHODS INDIRECT METHODS 1. Field sampling and laboratory measurements using dry combustion or wet combustion Accounting techniques  Stratified accounting with database  Remote sensing to infer factors determining above-ground carbon inputs 2.2 Laser-induced breakdown spectroscopy Atomic/ plasma-induced emission Visible 0.14 CHAPTER 2 — S OIL OR GA NIC CA R B ON D YNA MIC S A ND A SS ES S MENT M ETH OD S TABLE 2. in situ method Less accurate than mid-infrared in predicting soil organic carbon 0. Better than near infrared in distinguishing soil organic from inorganic carbon.000 Source: Adapted from Chatterjee and Lal (2009). the technology cannot directly distinguish soil inorganic from organic carbon Large footprint of about 2 m2 and sampling depth The technology is still at its infancy and needs to be calibrated for wide variety of soil types. and scanner must be adapted to capture large areas 10 100.1 Very fast—provides total soil carbon measurements in seconds. for example. Costs are prohibitive on per project basis 1 Rapid. (2001). currently. CARBON SEQUESTRATION IN AGRICULTURAL SOILS .1 Inelastic neutron scattering Nuclear/neutroninduced nuclear reactions Gamma rays 30 SAMPLED VOLUME (CM3) ADVANTAGES DISADVANTAGES In situ–based measurement of carbon. Emerging technologies for in situ determination  Laser-Induced Breakdown Spectroscopy  Inelastic Neutron Scattering (still being assessed for improved reliability for measurement)  Near-infrared and mid-infrared spectroscopy Source: Modified from Post et al. low cost.

Models provide a cost-effective means of estimating GHG emissions in space and time under a wide range of biophysical and agricultural management conditions. nitrogen. amount and type. and initial soil carbon. inorganic fertilizer timing. methane (CH4). soil temperature and moisture regimes. and emissions of nitrous oxide (N2O). Table 2. total nitrogen. plant N. planting rate.9). temperature. ISRIC-World Soil Information: A globally distributed soil spectral library: visible near-infrared diffuse reflectance spectra. and length of growing period Carbon stocks and fluxes. soil water dynamics. bulk density. wood density. carbon dioxide. deadwood. soil clay. maximum biomass in stand.9: Comparative Features of Some Carbon Estimation Models MODEL FEATURES KEY INPUTS KEY OUTPUTS CENTURY Simulates long-term dynamics of carbon. above. monthly rainfall. Progress is being made in developing and testing cost-effective soil carbon monitoring methods. Examples of national carbon accounting system and tools are presented in table 2. and tillage timing and type Total carbon. and agroforestry systems Simulation length. The Global Environment Facility (GEF) in collaboration with other partners is currently implementing the Carbon Benefits Project (CBP) to develop standardized. irrigation timing and amount. rainfall. and litter and soil organic carbon production RothC Estimation of turnover of organic carbon in topsoil Clay. and carbon dioxide (CO2) Plant growth data. phosphorus. fluxes of gases including N2O. carbon input into soil. P.and below-ground biomass. http://www. average monthly mean air temperature. total biomass and soil carbon. vegetation carbon stocks. application of remote sensing to estimate soil organic carbon controlling parameters. atmospheric and soil nitrogen inputs. NH3.15 C H A P T E R 2 — S O I L ORGANIC CARBON DYNAMICS A ND A SS ES S MENT METH OD S used to develop a spectral library for soils of the world. and management conditions. soil texture. yield tables. 1999).africasoils. and sulfur levels Total carbon. carbon content. crop rotation timing and type. precipitation. biomass carbon. ammonia (NH3). nitrogen. air temperature. initial carbon. EC O N O M I C A N D S E CT OR WORK 4 http://www. nitric oxide NO. total dry matter. and S content. Indirect estimation of soil organic carbon changes over large areas using simulation models is increasingly important to fill knowledge gaps about the biogeochemical processes of soil carbon sequestration. dinitrogen (N2). These include the selection of landscape units suitable for monitoring soil carbon changes. and mean annual increment in biomass and soil Biomass and soil carbon stock. and carbon in plant residue CO2FIX Simulates carbon dynamics of single/multiple species. and they are particularly useful for up-scaling site-specific information to the regional level. cost-effective methods of quantifying the carbon benefits of sustainable land management projects. soil water dynamics. incremental carbon stocks. spatially explicit biogeochemical modeling.3 The spectral library provides a valuable resource for rapid characterization of soil properties for soil quality monitoring and other agricultural applications. residue incorporation timing and amount. and cost-effectiveness indicators DNDC DeNitrification-DeComposition is used for predicting crop growth. and an estimate of the organic input Total organic carbon content and carbon content in microbial biomass PROCOMAP Equilibrium model for estimating carbon stocks Activity data. soil.pdf.net/sites/default/ files/ICRAF-ISRICSoilVNIRSpectralLibrary. they are particularly useful in the context of developing countries where land resources data are scarce. 3 World Agroforestry Centre.org/climatechange/carbon-benefits/ . forests. nitrogen leaching.11. pH. carbon sequestration. development of measurement protocols. phosphorus. and methane CH4 Source: This study. and scaling-up the results to the entire project area (table 2. Monitoring and verifying soil carbon sequestration at the project or regional scale require five components (Post et al. commercial crop yield. Monitoring the trends in soil carbon over a large geographical area through repeated sampling is mainly restricted to developed and few developing countries. and sulfur for different ecosystems Monthly mean maximum and minimum air temperature and total precipitation. Though the models could have limited accuracy. rotation period.9 compares the features of some of the biogeochemical models commonly used for soil carbon assessment.4 TABLE 2. Simulation models describe changes in soil organic carbon under varying climate. monthly open pan evaporation.unep. atmospheric nitrogen decomposition rate. nitric oxide (NO). crop yield.

the Agriculture and Land Use Tool (table 2. United States) The program supports countries’ efforts to understand current emission trends and the influence of land-use and management alternatives on future emissions. Voluntary Reporting of Greenhouse Gases-Carbon Management Evaluation Tool (http://www.7). as well as non-CO2 GHG emissions from biomass burning.and subnational-scale soil carbon stock variations in developing countries using RothC and Century models (table 2. The new suite of tools estimate and model carbon and other GHG flows under present and alternative management and measures. Multitemporal moderate resolution remote sensing such as Landsat Thematic Mapper and Moderate Resolution Imaging Spectroradiometer can provide information such as land-use and land cover change. and reporting methods.br/geoforest/pdf/group2/04%20-%20National%20carbon%20accounting%20system%20of%20Indonesia.pdf Forest Vegetation Simulator. http://carbon. The CBP comprises a national GHG inventory tool.aspx National Forest Carbon Monitoring. and soil moisture that can markedly improve up-scaling of soil carbon assessment. Models are useful for understanding soil properties–land management interactions and for predicting soil carbon sequestration. cellulose absorption index derived from remote imaging spectroscopy has been used to infer tillage intensity and residue quantity (Serbin et al. soil C stocks. http://www.11: Carbon Accounting Systems and Tools NAME DESCRIPTION AND INTERNET LOCATION Australia’s National Carbon Accounting System (NCAS) NCAS estimates emissions through a system that combines satellite images to monitor land use and land-use change across Australia that are updated annually.fed. multiple land uses. and ecosystem modeling—the Full Carbon Accounting Model. soil nitrous oxide emissions. land management.shtml Source: This study. leaf area index. and the data program. shrub land.cfs. and the GEF Soil Organic Carbon System that approximates national.au/government/initiatives/national-carbon-accounting. CARBON SEQUESTRATION IN AGRICULTURAL SOILS . http://www. 2009) Biogeochemical modeling Models are used to determine soil carbon changes over large areas because satellites cannot sense below-ground biological processes. They can simulate full ecosystem–level carbon balance. other ancillary field measurements.inpe.cometvr. sampling depth and volume.ca/index_e. http://www.16 CHAPTER 2 — S OIL OR GA NIC CA R B ON D YNA MIC S A ND A SS ES S MENT M ETH OD S TABLE 2. TABLE 2. It monitors forest definition.climatechange. Protocols for temporally repeated measurements at fixed locations will generally include stratification and selection of sampling sites. models. Canada (NFCMARS) NFCMARS is designed to estimate past changes in forest carbon stocks and to predict. enteric methane emissions. Recently. colostate. The three major activities linked are the remote sensing program. maps of soil type and soil carbon. forest inventory and modeling. United States The Forest Vegetation Simulator (FVS) is a family of forest growth simulation models. based on scenarios of future disturbance rates and management actions. and availability of historical data. and other stakeholders can be of help in selecting pilot areas and the extent to which the results can be extrapolated over the region. http://www. laboratory analyses. and changes in land management over time. geographical information system. They also monitor changes in carbon under specified land use and management. Source: Synthesized from Post et al.nrel. Since its initial development in 1973.us/fmsc/fvs/description/index. manure methane. temperature.nrcan.gc. Participation of local agronomists.11).at/carboinvent/workshop/1000_Peter_Stephens_ver_final. monthly maps of climate information.9). rice methane emissions. the modeling and measurement program for GHG accounting and reporting. management history. databases containing information on plant species. tillage practices. and estimation of the marginal cost of carbon sequestration. and humidity. existing database. changes in carbon stocks in the next two to three decades.edu/). and nitrous oxide emissions. Accounting and Reporting System.gov. and remote sensing.pdf New Zealand’s Carbon Accounting System The National Carbon Accounting System for New Zealand’s indigenous forest. crop yields. It can be used to estimate emissions and removals associated with biomass C stocks. and location and amount of crop residue for input into models. 1999. or several land management practices Up-scaling Scaling-up to large areas requires integration from a variety of sources including field measurements. Application of remote sensing Remote sensing can provide information on net primary productivity. The software accommodates Tier 1 and 2 methods as defined by the Intercontinental Panel on Climate Change. it has become a system of highly integrated analytical tools. land-use change. and soils was developed for the Ministry of the Environment by Landcare Research and Scion. measurement of bulk density. farmer organizations. It allows compilers to integrate global information system spatial data along with national statistics on agriculture and forestry and is designed to produce a consistent and complete representation of land use for inventory assessment. Development of protocol Changes in soil carbon can generally be estimated as changes in stocks (from direct measurement) or fluxes (using eddy covariance methods) (see table 2. http://www. The basic FVS model structure has been calibrated to unique geographic areas to produce individual FVS variants. soil properties. such as rainfall. crop rotations.dpi.joanneum.edu/projects/ghgtool/software.html Agriculture and Land Use National Greenhouse Gas Inventory Software (Colorado State University.fs.10: Components of Soil Carbon Monitoring at the Regional Scale COMPONENTS DESCRIPTION Selection of landscape units The selection will depend on responsiveness of the area to land management practices as determined by climate.php National Carbon Accounting System of Indonesia Provides monitoring capabilities for greenhouse gas (GHG) emissions/sinks to establish a credible reference emission level.colostate.

Ecosystems and Environment 87: 111–117. grasslands.. Chatterjee. supplemented by other existing methodologies and reviews of default coefficients. It is easy to use in the context of program formulation. 4: Agriculture. Niles. livestock. ad hoc coefficients. 10. It also has resources (linked tables and maps) that can assist in gathering the information necessary to run the model.or. and Lal. S. iges. Carbon assessment in EX-ACT is implemented in the following three steps: ƒ General description of the project (geographic area. B. J. “Total Carbon and Nitrogen in the Soils of the World. Bot. thereby indicating the overall effects on the carbon balance. and Cox. 2009. and Fernandes. M.org/sites/ v-c-s. it is cost-effective and requires a minimum amount of data. inputs. EC O N O M I C A N D S E CT OR WORK 17 .0. Policy Brief November 2009. E. and Foley. http://www. The Ex-Ante Appraisal Carbon-Balance Tool (EX-ACT. E. A detailed analysis of lessons learned in testing EX-ACT in World Bank agriculture projects can be found in World Bank (2012). IPCC. Land Use. 1–3. A. EX-ACT can provide ex ante assessments of the impact of agriculture and related forestry. 2001.4 CARBON ASSESSMENT IN THE WORLD BANK’S SUSTAINABLE LAND MANAGEMENT PORTFOLIO Carbon Assessment Using the Ex Ante Appraisal Carbon-Balance Tool The World Bank is increasingly looking to assess the carbon footprint of its operational work across sectors. The methodology currently being applied in the first African soil carbon project allows small-holder farmers in Kenya to access the carbon market and receive additional carbon revenue streams through the adoption of productivity-enhancing practices and technologies. Global Carbon Project. Sustainable Agricultural Land Management Methodology IPCC. A. afforestation/ reforestation. 2007. P. Guidelines for National Greenhouse Gas Inventories Vol. No. P. and duration of the project) ƒ Identification of changes in land use and technologies foreseen by project components using specific “modules” (deforestation.” Environmental Research Letters 2: 045023.pdf). IPCC. O..” Ann.fao. H.ipcc-nggip. farmers in developing countries (http://www.v-c-s. P.. R. London. http://www. K.C H A P T E R 2 — S O I L ORGANIC CARBON DYNAMICS A ND A SS ES S MENT METH OD S 2. “Temperature-Associated Increases in the Global Soil Respiration Record. 2009.. Brown. and water development projects on GHG emissions and carbon sequestration. it can easily be up-scaled at the program/sector level. 1993.” Nature 464: 579–582. J. S. REFERENCES Batjes. The BioCarbon Fund of the World Bank has recently developed a carbon accounting methodology to encourage adoption of sustainable land management practices by small-scale Kell. H. “On Farm Assessment of Tillage Impact on Soil Carbon and Associated Soil Quality Parameters. and Water Sequestration. “Managing Carbon Sequestration in Soils: Concepts and Terminology. “Breeding Crop Plants With Deep Roots: Their Role in Sustainable Carbon. and Forestry. 2010. ``Organic Carbon in Soils of the World. 192–194. Eswaran. Nutrient. Guidelines for National Greenhouse Gas Inventories Vol.B. Gibbs. Dufresne. provides protocol for quantifying carbon emissions and removals and includes guidelines for identifying baseline scenario and assessing additionality in all carbon pools relevant to sustainable land management projects. Ingram. climate and soil characteristics. when available..jp.” Agriculture. 2006. 108 (3): 407–418. 1996. D. 2011. “How Positive is the Feedback Between Climate Change and the Global Carbon Cycle?” Tellus 55B: 692–700. EX-ACT was developed following the IPCC guideline for national GHG inventory (IPCC 2006). A. annual/perennial crops.. Climate Change 2007: Synthesis Report—Summary for Policymakers. Reich.” European Journal of Soil Science 47: 151–163.. Emphasis is placed on cost-effective approaches that do not add excessively to the burden of project management. H. 2007. Friedlingstein. C... org/tc/exact/en/) has been developed with this objective in mind. 1996. fisheries. Fourth Assessment Report. rice cultivation. van den Berg.org/files/VM0017%20SALM%20Methodolgy%20 v1. The methodology. livestock. Bond-Lamberty. SALM is applicable to projects that introduce sustainable land management practices into croplands subject to conditions such that soil organic carbon would remain constant or decrease with time in the absence of the project. Intergovernmental Panel on Climate Change.’’ Soil Science Society of America Journal 57. and energy) ƒ Computation of carbon balance with or without the project using IPCC default values and. J. organic soils. forest degradation. referred to as Sustainable Agricultural Land Management (SALM). N. 2003. J. While EX-ACT primarily works at the project level. 104: 270–277. “Monitoring and Estimating Tropical Forest Carbon Stocks: Making REDD a Reality. I..” Soil Tillage Research. and Thomson.

Carbon Inventory Methods Handbook for Greenhouse Gas Inventory. P. Berlin. Springer-Verlag.. C. R. W.L.C.0 Lal. 1995. ed. “The Costs of Monitoring Changes in Forest Soil Carbon Stocks. R. et al. Carbon Foot-Printing of ARD Projects: Testing the Ex-Ante Carbon Balance Appraisal Tool. Makipaa.S. Monitoring and Beyond.. C. and Bliss.. M. N. K.. Post. Columbus.. CARBON SEQUESTRATION IN AGRICULTURAL SOILS . L. “Carbon Emission From Farm Operations. 2004. Ostwald. Robert et al.” Environment International 30: 981–990. 2012.. H. J. Izaurralde. W. Department of Agriculture. and Forestry. “Monitoring and Verifying Changes of Organic Carbon in Soil. Mann. N. Muukkonen. R. Rosenberg.” In Proceedings of the Symposium on Carbon Sequestration in Soils Science... 2003. ed. Natural Resources Conservation Service. Advances in Global Change Research. World Bank. 2008. R. R. Carbon Mitigation and Roundwood Production Projects.gov/use/worldsoils/mapindex/orders. Izaurralde. Intergovernmental Panel on Climate Change. N. “Soil Erosion and the Global Carbon Budget. N. and Bliss. Land Use.” Global Biogeochemical Cycles 9: 23–36. C. 2000.. Ravindranath..” Environment International 29: 437–450. “Global Soil Regions.” Boreal Environmental Research 13: 120–130. M. Cambridge. Hakkinen. R.18 CHAPTER 2 — S OIL OR GA NIC CA R B ON D YNA MIC S A ND A SS ES S MENT M ETH OD S Lal.. DC. and Potter.” Climatic Change 51 (1): 73–99. Washington.J. U. Land-Use Change. L. 2001. Watson. Mann. 1999.jpg. World Bank. Malone. “Global Patterns of Carbon Dioxide Emissions From Soils.” http://soils. Post. OH: Batelle Press. “Monitoring and Verification of Soil Organic Carbon Sequestration. and E. Izaurralde. Cambridge University Press. M. and M. K.usda. Raich.. 2008.

and mitigating GHG emissions (table 3. This chapter documents the evidence from the published literature on the impacts of agricultural land management practices and agricultural land-use changes on soil carbon sequestration in Africa. restoration of barren. depletion of soil organic carbon. less environmentally friendly due to nitrous oxide (N2O) emissions associated with N fertilizers. and increase income Introduction of improved crop varieties Application of biochar and other soil amendments Source: This study.19 C H A P T E R 3 — M E TA. the greenhouse cost of fertilizer production. and livestock and manure management. less environmentally friendly due to nitrous oxide (N2O) emissions associated with N fertilizers. and Latin America. Grassland. and emissions associated with transport of fertilizers Application of inorganic fertilizers and manure to stimulate biomass production—Chemical fertilizers are. The impacts of changes in agricultural practices on soil carbon stocks such as changes to crop rotation or reduced grazing are usually more subtle than those brought about by more dramatic changes in land use such as conversion of cropland to forest or grassland to tree crops. optimize water use. orchards.ANALYSE S OF SOIL CARBON SEQUES TR ATION Chapter 3: 3. increasing the resilience of agroecosystems. and woodlots into croplands helps to store more carbon.and below-ground biomass production and soil organic carbon accumulation Mulching/residue management—Improves soil moisture. grassland. Mitigation of GHG in agriculture can involve several practices such as avoiding the conversion of native forests and grasslands to croplands. but this has to be put in the perspective of emissions associated with the process of irrigation Use of cover crops/green manure increases the biomass returned to the soil and thus increases soil carbon stock Introduction of earthworms to improve aeration and aid organic matter decomposition in the soil profile Use of improved crop varieties—Improved crop varieties help to sequester carbon in the soil through increased above.1 META-ANALYSES OF SOIL CARBON SEQUESTRATION INTRODUCTION A range of practices has been suggested as important to soil carbon sequestration and thus of potential relevance to increasing crop yield. however. crop residues also prevent loss of carbon from the soil system Afforestation—Establishment of new forests on nonforest land (cropland. The main emphasis is on obtaining better estimates of soil carbon sequestration TABLE 3.1: Practices That Sequester Carbon in Forest. diversify production. and increases soil organic matter when incorporated into the soil. the greenhouse cost of fertilizer production.and below-ground biomass production Establishment of pasture on degraded land reintroduces large amounts of organic matter into the soil Agroforestry/tree-crop farming—Introduction of fruit trees. or degraded lands) increases carbon stock through the increase in above-ground biomass as well as greater organic materials input for soil decomposition Application of inorganic fertilizers and manure to stimulate biomass production—Chemical fertilizers are. however. and Cropland FOREST GRASSLAND CROPLAND Protection of existing forests—Avoided deforestation preserves existing soil C stocks and prevents emissions associated with biomass burning and soil exposure by land clearing Improved grassland management—Optimize stocking rates to reduce land degradation. and methane emissions through enteric fermentation No or reduced tillage—Reduces the accelerated decomposition of organic matter associated with intensive (conventional or traditional) tillage Reforestation—Increasing tree density in degraded forests increases carbon accumulation Introduction of improved pasture species and legumes to increase above. Asia. EC O N O M I C A N D S E CT OR WORK . or seriously degraded agricultural lands.1). prevents soil erosion. and emissions associated with transport of fertilizers Water management to increase productivity. abandoned. enhancing removal of carbon from the atmosphere through a range of soil and water management practices including crop diversification.

20

CH A PTER 3 — META -A NA LY S ES OF SOIL CA R B ON SEQU ES TR ATION

rates. This is one important element in making comprehensive assessments of the impact of soil quality on agricultural
sustainability and greenhouse mitigation potentials.

3.2

METHODS

Analysis
Most studies reported concentrations of carbon in soil
samples (Cc in g kg−1). These were converted to volumes and
then areas to calculate stocks (Cs in kg−1 ha−1) and sequestration rates (kg ha−1 yr−1) using bulk density (BD, in g cm−3) and
sample soil depth (D, in cm):

Searches and Data Sources
Searches were carried out using online database and
search tools, including ProQuest, Scopus, Sciencedirect,
SpringerLink, Wiley Science Library, and Google Scholar with
an emphasis on key terms such as soil organic matter, organic matter, soil organic carbon, soil carbon, carbon sequestration, soil sequestration, and soil properties, in combination
with geographical descriptors (e.g., countries and continents)
and terms for particular agricultural practices.
Inclusion-Exclusion Criteria
For soil fertility and surface management effects that are
commonly studied in agricultural science, only studies of at
least 3 years duration were included. A major effort was made
to collect data from as many long-term studies as possible.
Almost all studies adopted formal experimental designs,
setting up control and treatments. The variations applied in
the treatments accounted for the different levels of carbon
added to the soil. In a few cases where paired designs were
employed, logical contrasts were made with appropriate controls using final values of stocks under each treatment.
Experimental study designs are rare for land-use change
effects. Most adopted nonexperimental designs such as
chronosequence where adjacent plots of different ages were
compared, paired studies where adjacent plots of different
land uses and similar ages were compared, or repeated samples where same plot was measured over time. Only studies
of at least 4 years duration were included, and where repeated measures were made, sequestration rates for the longest
time interval were taken. A major reason for excluding papers
with data on different land uses was difficulty in assuming
particular sites could be taken as a reasonable control.
Effect Sizes
The effect of a land management practice was estimated by
comparing the final level of soil carbon stock in one treatment
with that practice and an appropriate control. Thus, all soil
carbon sequestration rates are estimates of effect size—the
difference with respect to a control—and thus represent the
marginal benefit of adopting that practice. Effect sizes were
estimated for all logical contrasts with sufficient information
provided in a paper.

Cs = BD x Cc x D x 10,000
In a few studies, value was given in terms of percent soil
organic matter. In these cases, concentrations of Cc (g kg−1)
were calculated as
Cc = 0.58 x OM% x 10
In some cases, only a single value, either initial or average
across treatments, was provided for bulk density. In these
cases, that value was assumed to apply to all treatments. If
no bulk density information was provided in a paper (or other
reports about the same study cited by that paper), then bulk
density was estimated using known pedotransfer functions
(that is, simple regression equations) developed for that region
or extracted from the International Soil Reference Information
Center–derived soil properties database (www.isric.org).
Effect sizes and importance of contextual variables (e.g.,
temperature, precipitation, duration, and soil type) were
summarized by means and 95 percent confidence intervals
for the mean. Associations of the context variables with carbon sequestration were assessed by grouping observations
into a few classes so that nonlinear patterns could be clearly
identified. Geographical distribution of datasets is shown in
figure 3.1, while the characteristics of the estimates with
respect to duration of study, soil sampling depth, and experimental design are shown in Appendix 3.1.

3.3

RESULTS

Contextual Factors and Soil Carbon Sequestration
Climate
Climate significantly influences large-scale patterns of soil
carbon sequestration. In this study, higher sequestration
rates were observed in the wettest locations (figure 3.2).
There was also a trend to lower sequestration rates in the
coolest and warmest conditions (figure 3.3). Sites in warmer
and middle temperature regions tended to accumulate soil
carbon more rapidly than those in colder regions, whereas
semi-humid areas had higher average rates than their semiarid counterparts. Potter et al. (2007) explored interactions
with residue management practices in maize fields at six

CARBON SEQUESTRATION IN AGRICULTURAL SOILS

21

C H A P T E R 3 — M E TA- ANALYSE S OF SOIL CARBON SEQUES TR ATION

FIGURE 3.1: Geographical Distribution of Carbon Sequestration Estimates

Carbon sequestration
number of estimates
1–10
11–30
31–50
51–100
101–200
201–630

Source: This study.

sites across a wide range of annual temperature regimes in
Mexico and discovered that as temperature increased, more
crop residues needed to be retained to increase levels of soil
organic carbon. An increase in soil temperature exacerbated
the rate of mineralization, leading to a decrease in the soil
organic carbon pool (SOC). However, decomposition byproducts at higher temperatures may be more recalcitrant
than those at lower temperatures.

soil profiles give some indication of humus, clay minerals, or
metal oxides accumulating in their layers. In Asia, the highest
sequestration rates and variability were observed on oxisols,
formed principally in humid tropical zones under rain forest,
scrub, or savanna vegetation on flat to gently sloping uplands. Oxisols are typically found on old landscapes that have
been subject to shifting cultivation for several years.
Duration

Soils
Soil type, especially those with a higher clay content, leads to
higher carbon sequestration rates. However, obtaining comparable data is difficult as not all studies provide sufficient
information on soil properties, and those that do use different soil classification schemes at different levels of detail. As
a first-level analysis, the reported soil types were reclassified
into major soil orders of the U.S. Department of Agriculture
classification system (figure 3.4). Carbon sequestration rates
were highest and also highly variable on inceptisols in Africa
and Latin America. Inceptisols are relatively young soils
characterized by having only the weakest appearance of horizons, or layers, produced by soil-forming factors. Inceptisol

EC O N O M I C A N D S E CT OR WORK

Longer term studies on average have resulted in lower
sequestration rates, as would be expected from saturation
(figure 3.5). Most of the potential soil carbon sequestration
takes place within the first 20 to 30 years. The pattern of
change in sequestration rates is nonlinear and differs between major groups of practices, with the highest rates at
intermediate times and low or even negative rates in the
short term.
Nutrient Management
Fertilizer use sequesters carbon by stimulating biomass production. Judicious fertilizer application also counters nutrient
depletion, reduces deforestation and expansion of cultivation

22

CH A PTER 3 — META -A NA LY S ES OF SOIL CA R B ON SEQU ES TR ATION

FIGURE 3.2: Soil Carbon Sequestration and
Precipitation

FIGURE 3.3: Soil Carbon Sequestration and
Temperature

Africa

Africa
3,000
carbon sequestration (kg C/ha/yr)

carbon sequestration (kg C/ha/yr)

3,000
2,500
2,000
1,500
1,000
500

2,500
2,000

1,500
1,000

500

0

0
<500

500–1,000

1,001–1,500

<20

<1,500

annual precipitation (mm)

carbon sequestration (kg C/ha/yr)

carbon sequestration (kg C/ha/yr)

>30

Asia

Asia

1,250

1,000

750

500

250

800

600

400

200
<500

500–1,000 1,001–1,500
annual precipitation (mm)

< 10

1,500+

10 – 20

20 – 30

30+

mean annual tempeature (°C)
Latin America

Latin America
800

1,200
carbon sequestration (kg C/ha/yr)

carbon sequestration (kg C/ha/yr)

20–25
25–30
mean annual temperature (°C)

600

400

200

1,000
800
600
400
200
0
–200

<500

Source: This study.

500–1,000 1,000–1,500
annual precipitation (mm)

1,500+

<15

15.20

20.25

25+

mean annual temperature (°C)
Source: This study.

CARBON SEQUESTRATION IN AGRICULTURAL SOILS

some studies show that integrated management of N. Asia Mollisols Inceptisols Entisols Aridisols Andisols Alfisols 0 1.000 2. K = Potassium were significantly higher than other combinations (Figure 3. Alvarez’s (2005a) analysis of a global dataset indicated that for every additional tonne of nitrogen fertilizer applied.5 percent increase in soil carbon in agricultural ecosystems (Lu et al.000 3.000 Across the full dataset.000 3. P.4: Soil Carbon Sequestration and Soil Order Africa ƒ Adjusting application rates based on assessment of crop needs Vertisols Ultisols ƒ Minimizing losses by synchronizing the application of nutrients with plant uptake soil type Oxisols ƒ Correcting placement to make the nutrients more accessible to crop roots (microfertilization and microdosing) Mollisols Inceptisols ƒ Using controlled-release forms of fertilizer that delay its availability for plant uptake and use after application Andisols Alfisols 0 1. Aggregating across locations and cropping systems there was no significant association between level of N applied across annual cropping cycles and carbon sequestration rates (figure 3. and K fertilizers is important to maintaining or increasing soil carbon and nitrogen and thus soil fertility. EC O N O M I C A N D S E CT OR WORK Biofertilizers are an essential component of organic farming.000 carbon sequestration (kg C/ha/yr) Source: This study. P = Phosphorus.000 4. Soil organic carbon levels clearly increased under nitrogen fertilization only when crop residues were returned to the soil. in some cases.2). Strategies to promote nutrient use efficiency include the following: Mollisols Inceptisols Entisols Andisols Alfisols –2. 2011). They contain living microorganisms that colonize the rhizosphere and promote plant growth by increasing the supply of nutrients through nitrogen fixation or enhancing the availability of primary nutrients to the host plant by solubilizing phosphorus and other nutrients. Another meta-analysis at the global level concluded that addition of nitrogen fertilizer resulted. and increases crop yields. two more tonnes of soil organic carbon were stored in fertilized than unfertilized plots.000 3.ANALYSE S OF SOIL CARBON SEQUES TR ATION FIGURE 3. Latin America Vertisols Ultisols Oxisols soil type to marginal areas. and 264 kg C ha−1 yr−1 for Africa (table 3. in a 3. 222 kg C ha−1 yr−1 for Asia.6). the combination of fertilizer with locally available manure sources.000 4.7). The majority of studies have designs focused on the influence of different levels of nitrogen and. Phosphorus and Potassium compound fertilizers N = Nitrogen.Nitrogen. studied average sequestration rates with NPK . on average. Within individual experiments.000 carbon sequestration (kg C/ha/yr) 4. The microorganisms in 23 .000 2.000 2.000 carbon sequestration (kg C/ha/yr) Vertisols Ultisols Oxisols soil type ƒ Using nitrification inhibitors that hold-up microbial processes leading to nitrous oxide formation The average effect size of applying fertilizer was an additional 124 kg C ha−1 yr−1 sequestered for Latin America.C H A P T E R 3 — M E TA.000 0 1.000 –1.

500 500 Tillage and residue management 1.600 4.000 1.000 carbon sequestration (kg C/ha/yr) carbon sequestration (kg C/ha/yr) 5–10 duration of study (years) >30 3.000 400 750 200 500 250 0 <5 5–10 10–20 20–30 duration of study (years) 30+ <5 5–10 10–20 20–30 duration of study (years) 30+ CARBON SEQUESTRATION IN AGRICULTURAL SOILS .000 Nutrient manangement 2.500 1.000 500 Land-use change 4.250 600 1.500 3.000 carbon sequestration (kg C/ha/yr) 1.000 2.000 1.500 2.500 3.000 1.5: Soil Carbon Sequestration and Time Africa carbon sequestration (kg C/ha/yr) 4.24 CH A PTER 3 — META -A NA LY S ES OF SOIL CA R B ON SEQU ES TR ATION FIGURE 3.000 800 600 400 200 0 <5 0 5–10 11–20 duration of study (years) <5 11–20 4.500 3.500 1.000 2.400 1.200 1.000 500 0 0 <5 5–10 duration of study (years) <5 11–20 5–10 11–20 20–30 >30 duration of study (years) Asia Tillage and residue management All carbon sequestration (kg C/ha/yr) 1.500 2.500 2.500 1.000 All 3.

500 Nutrient management 750 5–10 10–20 20–30 duration of study (Years) 1. EC O N O M I C A N D S E CT OR WORK 30+ <5 5–10 10–20 20–30 duration of study (years) 30+ .000 200 500 0 0 <5 5–10 10–20 20–30 duration of study (years) Land-use change <5 30+ 5–10 10–20 20–30 duration of study (years) 30+ Latin America All 1.000 1.500 carbon sequestration (kg C/ha/yr) carbon sequestration (kg C/ha/yr) 1.500 0 <5 5–10 10–20 20–30 duration of study (years) Source: This study.000 Nutrient management 2.500 800 2.25 C H A P T E R 3 — M E TA.000 0 500 0 –500 <5 10–20 5–10 20–30 <5 30+ duration of study (Years) carbon sequestration (kg C/ha/yr) carbon sequestration (kg C/ha/yr) 500 250 0 30+ Land-use change 1.200 800 600 400 200 Tillage and residue management 1.000 600 1.ANALYSE S OF SOIL CARBON SEQUES TR ATION 95% CI carbon sequestration (kg C/ha/yr) 1.000 –250 –1.500 400 1.000 500 0 –500 –1.

26 CH A PTER 3 — META -A NA LY S ES OF SOIL CA R B ON SEQU ES TR ATION FIGURE 3.6: Soil Carbon Sequestration and Application Levels of Nitrogen Fertilizer (Means and 95 Percent Confidence Intervals. FIGURE 3. n = 285) carbon sequestration (kg C/ha/yr) 600 400 200 0 <100 100–200 200–300 300+ N fertilizer (kg N/ha/yr) Source: This study. NK = Nitrogen and Potassium only. CARBON SEQUESTRATION IN AGRICULTURAL SOILS . Note: N = Nitrogen. NP = Nitrogen and Phosphorus only.7: Soil Carbon Sequestration and Fertilizer Combinations (Means and 95 Percent Confidence Intervals. Note: N = Nitrogen only. NPK = combination of Nitrogen. Phosphorus and Potassium. PK = Phosphorus and Potassium only. n = 285) 500 carbon sequestration (kg C/ha/yr) 400 300 200 100 0 N NP PK NK NPK fertilizer mix Source: This study.

27 C H A P T E R 3 — M E TA. Biofertilizers are more environmentally friendly and cost-effective relative to chemical fertilizers. yields of maize and maize-wheat systems increased over the longer term. Close spatial integration is required for crop-livestock interactions involving crop residues. which were 1. These benefits have already been recognized in efforts to divert organic waste from landfills.960 3 Chemical fertilizer 124 −15 262 74 Manure 455 23 887 25 Asia Biofertilizer Latin America Source: This study. and Hakamata 2008) have pointed to trends of declining livestock numbers and speculated on impacts of this on manure application practices.8 times greater for compost than for manure. manure. these land emission impacts were small when compared to soil C sequestration rates. economic movement of crop residues. Paisancharoen. Methane emissions can also be minimized by displacing anaerobic storage options with aerobic decomposition. 243 C ha−1 yr−1 more in Asia. Manure application to agricultural soils can reduce nitrous oxide emissions by displacing N fertilizer use. suggesting that the organic matter stabilization during composting reduces post-application respiration losses. 2007) and Thailand (Matsumoto.4 t C ha−1 yr−1. However.ANALYSE S OF SOIL CARBON SEQUES TR ATION TABLE 3.2). and Desjardins (2005) found that compared to untreated manure storage. yielding 61 kg C ha−1 yr−1 more in Africa.2: Nutrient Management and Soil Carbon Sequestration Rates (kg C ha−1 yr−1) PRACTICE MEAN LOWER 95 PERCENT CONFIDENCE INTERVAL OF MEAN UPPER 95 PERCENT CONFIDENCE INTERVAL OF MEAN NUMBER OF ESTIMATES Africa Chemical fertilizer 264 169 359 30 Manure 325 224 427 30 Chemical fertilizer 222 157 288 297 Manure 465 374 556 146 1. Studies in Nepal (Acharya et al. and animal power (table 3. Integration in the temporal domain connotes that crop and livestock production can take place simultaneously (in parallel) or can be temporally segregated (in sequence). hindering interaction. In China. Yields EC O N O M I C A N D S E CT OR WORK also increased with manure application and accumulation of soil carbon but with patterns that depend on crop. moisture content. the gains happened in the first few years and were not followed by further yield improvements (Zhang et al. Trzcinski. and Min (2008) examined GHG fluxes following land application of solid beef manure and composted dairy manure over a 3-year period. Manure sequestered more carbon than fertilizer.9 versus 0. Temporal integration can only occur after some form of spatial integration has taken place.7 t CO2e ha−1 yr−1). Fronning. and livestock is markedly curtailed. and financial income (Sumberg 2003).3). manure. Crop-livestock integration can occur in space. and 331 kg C ha−1 yr−1 more in Latin America (table 3. The agronomic and economic justification for the integration is based on the exchange of four main types of resources: crop residues.01 t CO2e ha−1 yr−1). 2009). Thelen. The impact of manure on soil carbon sequestration is best realized in farming systems that integrate crops and livestock. Three studies reviewed indicate that biofertilizers sequestered about 1. composting reduced total GHG emissions (CH4 and N2O) by 31 to 78 percent. manure. while in rice-based systems. biofertilizers restore the soil’s natural nutrient cycle and help in building soil organic matter. depending on carbon-to-nitrogen ratio. The spatial domain integration is based on the idea that crops and livestock activities can be colocated with the level of integration increasing as the scale becomes smaller. Net CH4 flux was minimal (less than 0. Pattey. time. or ownership domains. while untreated manure application generated higher N2O emissions than did compost (0. One major constraint is the availability of manure and labor costs associated with collecting and processing it. management. and aeration status.459 −42 2. and the latter is important given the . At large distances (scale). animal power. The impact of composting on emissions post-land application is of further interest.

The establishment of bioenergy plants to meet the demand for biofuel may also help. while others looked at the effects of grazing crop residues on soil carbon sequestration. desirable results will be achieved if integrated foodfeed-energy systems are tailored to specific local conditions. Note: * = little importance. ƒ intercepting raindrops.8). Cereals also have higher concentrations of lignin that are resistant to decomposition. including tillage method. and biofuel. While ownership may increase the efficiency of the beneficial effects of interaction. In general. As large carbon losses occur under very wet conditions. ** = some importance.4). has three primary purposes: to facilitate seed germination CARBON SEQUESTRATION IN AGRICULTURAL SOILS . Others were on the effects of sugar cane residues on sequestration. thereby allowing water to gently percolate into the soil. crop residue. the formal and informal links between crop and livestock producers for accessing manure. thereby promoting control and secure access to resources. most studies looked specifically at the effects on soil carbon sequestration of mulching or incorporating residues relative to burning. ƒ increasing aggregation of soil particles. Tillage. while low-quality residues tend to immobilize nitrogen. and using cookstoves for rural dwellers in Malawi and using agroforestry systems for food. integration in the management domain implies that management of crop and livestock production may or may not be in the hands of the same entity and that management may not necessarily coincide with ownership of both crops and livestock. agronomic productivity.3: Relative Importance of the Four Domains of Integration on Crop-Livestock Interaction SPACE TIME Crop residue *** ** * ** Manure *** * * ** Animal power *** *** * * * ** *** * Financial income OWNERSHIP MANAGEMENT Source: Adapted from Sumberg (2003). and ƒ reducing run-off and erosion. but it requires more labor. The quality and quantity of residues markedly influence the amount of carbon sequestered (figure 3. Crop-livestock integration can minimize the trade-off in the use of residues for feed (see the section of this report on nutrient management on page 21). Integration in the ownership domain underscores the fact that a given croplivestock combination can be owned by the same or a different entity. and bioethanol production in Mozambique. integration in the ownership domain is not required for beneficial croplivestock interaction. the best results are obtained when residues are applied shortly before the beginning of the rainy season. thatch. the agricultural preparation of the soil for planting. and GHG emissions by ƒ aiding nutrient cycling. In Latin America. use of straw from rice and other crop residues was found to be prevalent in Asia. The quantity of residue produced is a function of the cropland area and agronomic practices. High-quality residues of perennial legumes are generally the most effective in supplying nitrogen in the short to medium term. Crop residue management influences soil resilience. fodder. The effects of crop residues and mulches on carbon sequestration are highest in Latin America and lowest in Africa (table 3. Last. ƒ lowering soil evaporation. Examples include intercropping maize and pigeon pea. income generation. Cereals are two to three times better than legumes at sequestering carbon. *** = much importance. Zero grazing involving the confinement of livestock in a stall and developing a cut-and-carry fodder system can make for more residue retention on the field. seasonality of feed and water for livestock. integration in the management domain is not a prerequisite for successful beneficial crop-livestock interaction (Sumberg 2003). Apart from biomass from trees.28 CH A PTER 3 — META -A NA LY S ES OF SOIL CA R B ON SEQU ES TR ATION TABLE 3. or power implies that though desired. However. Controlled grazing and the establishment of plots of permanent forages for direct grazing can also reduce conflicts between soil organic matter accumulation and grazing needs. Crop Residue Management and Tillage Crop residues are an important renewable resource for agroecosystems. One of the main barriers to the use of crop residues and mulch for soil fertility management is the numerous competing uses for feed.

29 C H A P T E R 3 — M E TA. TABLE 3. Crop Residue Management.4: Tillage. EC O N O M I C A N D S E CT OR WORK .ANALYSE S OF SOIL CARBON SEQUES TR ATION PHOTO 3.258 56 Mulches 748 262 1.108 16 Cover crops 314 108 520 33 No-tillage 535 431 639 249 Asia Latin America Source: This study.1: Crop Residue Management in Irrigated Fields in Indonesia Source: Curt Carnemark/World Bank. and Soil Carbon Sequestration Rates (kg C ha−1 yr−1) PRACTICE MEAN LOWER 95 PERCENT CONFIDENCE INTERVAL OF MEAN UPPER 95 PERCENT CONFIDENCE INTERVAL OF MEAN NUMBER OF ESTIMATES Africa Crop residues 374 292 457 46 Mulches 377 159 595 6 Cover crops 406 298 515 24 No-tillage 370 322 418 108 Crop residues 450 379 521 189 Mulches 565 371 759 53 Cover crops 414 233 594 38 No-tillage 224 97 351 48 Crop residues 948 638 1.

Depending on the amount of residue left on the soil surface. increase in soil erosion and loss of nutrients.8: Mean Soil Carbon Sequestration and Levels of Residue Returned 1. Conservation agriculture in Zambia entails (1) dry season land preparation using minimum tillage methods and utilizing fixed planting stations (small shallow basins). CARBON SEQUESTRATION IN AGRICULTURAL SOILS . the holistic agricultural production system that integrates management of soil. entails motorized multiple farm operations with mold board. the 95 percent confidence intervals are shown as whiskers.000 carbon sequestration (kg C/ha/yr) 800 600 400 200 0 <3 3–5 5–8 8+ residue application (t/ha/yr) Source: This study. decrease in infiltration rate. and ƒ crop rotation and diversification using legumes and green manure or cover crops (figure 3. tillage systems can be broadly classified into conventional. disk. Canada. and (3) rotation of grains with legumes in the field. In this study. Africa lags behind with only about 500. Conservation tillage systems leave the most crop residues on the surface. While plowing loosens and aerates the topsoil and facilitates seedling establishment. manures and crop residues into the soil. increase in evaporation loss. more appropriately referred to as intensive tillage. The conventional method. Conventional tillage leaves the least residue on the soil surface.30 CH A PTER 3 — META -A NA LY S ES OF SOIL CA R B ON SEQU ES TR ATION FIGURE 3. to incorporate fertilizer. and they are the precursor to conservation agriculture. Most of the conservation tillage systems are large-scale farms in the United States. carbon sequestration under conservation tillage ranged from 224 kg ha−1 yr−1 for Asia to 535 kg ha−1 yr−1 for Latin America (table 3.000 ha under conservation agriculture. Conventional tillage should not be confused with traditional tillage techniques involving manual or animal-drawn operations. Notes: n = 165. and to control weeds. Recent experience in Zambia—conservation agriculture with trees—suggests that the system holds promise for replenishing soil fertility and improving productivity and rural livelihoods. water. and reduction in soil organic matter. reduced. plow. by creating a smooth. it can lead to many unfavorable effects including soil compaction. and Australia. destruction of soil aggregates.2). Brazil. Conservation agriculture is based on ƒ minimum soil disturbance through mechanical tillage. Argentina. and conservation tillage (figure 3. uniform soil surface for planting. and harrow for seedbed preparation.9). 2011). and biological resources (Liniger et al. ƒ permanent soil cover through residue management. (2) retention of crop residue from previous harvests in the field or use of other mulches from the tree component (Faidherbia albida) or other cover crops.4).

To avoid yield depression during transition period (3 to 5 years). aims for 100% soil cover and does not involve soil disturbance through tillage. nutrients.000 kg ha-1 crop residue equivalent) 15% to 30% residue cover on the soil (500 to 1. farmers adopting the system have been better able to plant close to the onset of the rains. and they also help in . cover crops. Also. and field cultivators. Only the soil area containing seed rows are tilled. fertilizer should be applied in slightly higher quantities. less tillage reduces labor costs. The soils are tilled at specific intervals e. By eliminating the need for laborious land preparation.000 farmers used this system at the end of 2010.000 kg ha-1 crop residue equivalent) Strip tillage Mulch tillage It uses minimum tillage by combining the soil aeration benefits of conventional tillage with the soilprotecting advantages of no tillage. Source: This study. The ridges are formed from crop residues that are left on the soil. appropriate cover crop mix for weed suppression is essential. at the introduction of a crop in the rotation sequence. Examples include cowpea. hills or bunds that provides warmer conditions for plant growth. Green manure crops are commonly leguminous crops with high nitrogen content. while the top of the ridges are leveled off at planting. The rows are maintained in the same location each season. the residue cover prevents soil erosion. The tree component provides mulch and nutrients. organic matter. conserves soil moisture and helps increase soil organic matter. Ridge tillage Ridge tillage is similar to the traditional systems with planting on preformed ridges. It also includes planting operations such as hoe drills and air seeders. Strip tillage requires higher precision planters compared to no tillage system. Cover crops help to improve soil macronutrients and micronutrients and are termed green manure because of their ability to enhance soil fertility. improve water use efficiency and reduce energy use. Residue management is used in conjunction with crop rotation. and adjustment of planting density. For instance. yields have doubled for maize and increased by 60 percent for cotton compared to conventional tillage system. Soil erosion on strip tilled farms is much lower than for conventional tillage. reduce erosion.9: Classification of Tillage Systems Based on Crop Residue Management Tillage Systems Conventional tillage Less than 15% residue cover on the soil (< 500 kg ha-1 crop residue equivalent) No tillage Also called zero tillage.g. Reduced tillage Conservation tillage Greater than 30% crop residue on the soil (>1. or every other year depending on cropping sequence. Like other conservation tillage systems. groundnut and mucuna. the practice of growing cover crops in situ was distinguished from mulches and crop residues of main harvested crops. cover crops can be used to control weeds and supply nutrients. EC O N O M I C A N D S E CT OR WORK Cover Crops In this study.ANALYSE S OF SOIL CARBON SEQUES TR ATION FIGURE 3. The system is mainly used on poorly drained soils. sweeps. a rotational system may include both mulch tillage and no tillage.000 farmers by 2011. The primary purpose of mulch tillage is to increase soil organic matter and tilth. Cover crops can also improve soil quality by increasing soil organic carbon through their biomass.31 C H A P T E R 3 — M E TA. or rotation from annual to perennials. and this figure was projected to rise to 250. Higher soil moisture also helps to increase cropping intensity rather than leave the field fallow. Soil is disturbed prior to planting and crop residues are incorporated using chisels. Strip tillage allows for a better seedbed and for nutrients to be better adapted to the plant’s needs. Using conservation agriculture. Rotational tillage This is a system in which different tillage methods are used to establish different crops during a crop rotation sequence. Helps to increase soil moisture. As an option to increased herbicide use. representing some 30 percent of the population of small-scale farmers in Zambia. Over 180. and crop yields.

Improved irrigation sequestered carbon the most. and cropping systems rather than effects of cropping intensity. Conveyance and distribution efficiency are also important measures in irrigation. followed by maize. Two variants of crop rotation observed in the review are rotation intensification and diversification (table 3. Agroforestry Agroforestry is an integrated land-use system combining trees and shrubs with crops and livestock. Intensifying rotation means replacing a fallow with another crop. and tef. improving soil aggregate stability.10). Rotation diversification is different in Africa compared to Latin America. while diversifying rotation implies altering cropping sequences within or across years while keeping the same number of crops in the rotation..5: Crop Rotation and Soil Sequestration Rates (kg C ha−1 yr−1) MEAN LOWER 95 PERCENT CONFIDENCE INTERVAL OF MEAN UPPER 95 PERCENT CONFIDENCE INTERVAL OF MEAN NUMBER OF ESTIMATES Diversify rotation 378 306 451 49 Intensify rotation 342 277 407 55 345 87 604 43 PRACTICE Africa Asia Intensify rotation Latin America Intensify rotation 331 165 496 25 Diversify rotation 136 −62 334 43 Source: This study. In Africa. and tree legumes. followed by sorghum.g. The practice aims at minimizing the effects of seasonal variations in water availability due to droughts and dry periods and enhancing the reliability of agricultural production. and ƒ diversifying the rotation to include nitrogen-fixing legumes. Rainwater harvesting is particularly important for rain-fed agriculture in arid and semiarid regions. protecting the soil from surface runoff and suppressing weeds. increased soil water management. Rotating to a different crop such as cowpea or soybean usually results in higher grain yields when compared to continuous cropping of maize. ƒ producing large amounts of biomass and residue for soil protection and incorporation in the soil.32 CH A PTER 3 — META -A NA LY S ES OF SOIL CA R B ON SEQU ES TR ATION The apparent lower level for double compared to single or triple cropping may reflect differences in soils. managing excess water. and reduced pest and diseases. TABLE 3. millet. The recommended crop rotation strategies include Water Management Improved water productivity in agriculture is achieved by reducing water loss. Crop Rotation Crop rotation is a key complementary practice for successful implementation of no-tillage. sesame. and maximizing water storage. grain crops followed by legumes) or variety from the previous crop. but variation is high (figure 3. In the Sahel. Terracing on steep slopes and cross-slope barriers helps in reducing surface runoff. and the planned rotation may be for 2 or more years. cassava. reduced soil erosion. groundnuts. a typical cropping sequence is millet/sorghum. thereby There is a tendency toward higher sequestration rates in triple cropping systems.6). while in Ethiopia. cowpea. ƒ including perennial crops in the rotation. harvesting water. yams. It also contributes to agro-ecosystem resilience by controlling runoff and soil erosion.5). Other benefits of crop rotation include improved soil fertility. the traditional element of crop rotation is the replenishment of nitrogen through the use of legumes in sequence with other crops. Crop rotation is the deliberate order of specific crops sown on the same field. ƒ maintaining a continuous sequence of living vegetation. the sequence is usually maize/barley. CARBON SEQUESTRATION IN AGRICULTURAL SOILS . climate. Agroforestry maintains soil organic matter and biological activity at levels suitable for soil fertility. The succeeding crop may be of a different species (e. while terracing sequestered the least (table 3.

FIGURE 3.10: Mean Soil Carbon Sequestration and Cropping Intensity carbon sequestration (kg C/ha/yr) 1.250 1.2: Water Management in a Field in India Source: Ray Witlin/World Bank.000 750 500 250 Single Double cropping intensity Source: This study. Note: The 95 percent confidence intervals are shown as whiskers (n = 536).500 1.ANALYSE S OF SOIL CARBON SEQUES TR ATION PHOTO 3.33 C H A P T E R 3 — M E TA. EC O N O M I C A N D S E CT OR WORK Triple of more .

a characteristic that makes it dormant and sheds its leaves during the early rainy season and leafs out at the onset of the dry season. and water. The shade provided by the trees helps in moderating microclimate and reducing crops and livestock stress and helps to improve crop yields.428 477 2.34 CH A PTER 3 — META -A NA LY S ES OF SOIL CA R B ON SEQU ES TR ATION TABLE 3.805 22 421 276 566 15 Rainwater harvesting 1.086 405 1. sorghum.193 581 1. Faidherbia is widespread throughout Africa.767 4 Improved irrigation 1. This makes Faidherbia compatible with food crop production because it does not compete for light. cotton. an Acacia species native to Africa and the Middle East.379 10 571 −59 1. CARBON SEQUESTRATION IN AGRICULTURAL SOILS . nutrients.3: Maize Growing under Faidherbia Albida Trees in Tanzania Source: World Agroforestry Centre. millet.201 34 Cross-slope barriers Terracing Asia Latin America Improved irrigation Source: This study. PHOTO 3. and occurs in different ecosystems ranging from dry lands to wet tropical climates. One of the most promising fertilizer tree species is Faidherbia albida. Farmers have frequently reported significant crop yield increases for maize.122 33 1. and groundnut when grown in proximity to Faidherbia. reducing losses of water and nutrients.6: Water Management and Soil Carbon Sequestration Rates (kg C ha−1 yr−1) PRACTICE MEAN LOWER 95 PERCENT CONFIDENCE INTERVAL OF MEAN UPPER 95 PERCENT CONFIDENCE INTERVAL OF MEAN NUMBER OF ESTIMATES Africa Rainwater harvesting 839 556 1. It fixes nitrogen and has the special feature of reversed leaf phenology. thrives on a range of soils.

and Tephrosia vogelii. EC O N O M I C A N D S E CT OR WORK .359 755 1. The responses over time vary in different studies and may be affected by biomass harvesting. Nitrogen-fixing plants are normally used because they are generally sturdy.964 44 Improved fallow 2. deep rooted.7). the incorporation of more trees reduces spacing between crops. the area under tropical plantations has increased drastically since the 1960s from 7 Million hectares (Mha) in 1965 to 21 Mha in 1980. and fix atmospheric nitrogen.421 14 Alley farming 1.063 7 Source: This study. while the highest effects for trees recorded in Africa was 1. the switch was to perennial grasses used as fodder for livestock.The estimates covered cocoa in Ghana and Cameroon. During the fallow period. Land-Use Changes The review captured diverse categories of land-use changes in Asia and Latin America compared to Africa (table 3. sesban. The average soil carbon sequestration rate of tree-crop farming is approximately 1. releasing additional nutrients to the subsequent crops.365 516 2. drought tolerant.610 125 Intercropping 629 162 1.5 t ha−1 yr−1).ANALYSE S OF SOIL CARBON SEQUES TR ATION Improved fallow involves the use of fast-growing trees to accelerate the process of soil rehabilitation and thereby shorten the length of fallow sequester carbon the most (about 2. while leaf litter protects the soil from erosion. coffee in Burkina Faso. their roots remaining in the soil gradually decompose. Cocoa planted at low plant density and under shade stores more carbon per unit area of soil than an equivalent area of cocoa planted at high density without shade. The highest effects recorded in Latin America for intercropping were 1. enriches the soil with nutrients.1 t ha−1 yr−1.065 270 1. and cashew and teak plantation in Nigeria. tropical plantations are needed for timber and. Thus. When the trees are removed after fallow.860 43 Asia Latin America Include trees in field Diversify trees 1.7: Agroforestry and Soil Carbon Sequestration Rates (kg C ha−1 yr−1) PRACTICE MEAN LOWER 95 PERCENT CONFIDENCE INTERVAL OF MEAN UPPER 95 PERCENT CONFIDENCE INTERVAL OF MEAN NUMBER OF ESTIMATES Africa Include trees in field 1. the plants accumulate nitrogen from the atmosphere and deep layers of the soil.204 798 1. oil palm in Cote d’Ivoire. Competition with crops is an important trade-off.047 46 Tree-crop farming 1. Gliricidia sepium. and helps to conserve moisture. rubber plantation in Nigeria and Ghana. easy to establish.541 17 1. In virtually all cases.089 116 2. and 187 Mha in 2000. Replacing annual crops with perennials increased soil carbon sequestration on average by 1 t C ha−1 yr−1 in Asia and by 0.8). exotic tree species in Ethiopia. sun hemp.213 6 Intercropping 1. Although including the nitrogen-fixing tree Dalbergia sisso leads to more accumulation of organic carbon in the soil.35 C H A P T E R 3 — M E TA.4 t C ha−1 yr−1.886 2. 43 Mha in 1990. In addition to C sequestration in biomass and soil. On TABLE 3. Examples of species used for improved fallow include pigeon pea. Intercropping examines the effects of crops on soils where there are trees. as opposed to the effects of including trees where there are crops. as fuel for cooking. and shading of crops by trees may reduce crop yields.5 t C ha−1 yr−1 in Latin America. more importantly.458 869 2.413 1. The improved fallow trees and shrubs are left in the field for several months or years.2 t ha−1 yr−1 (table 3.941 71 Include trees in field 562 220 904 58 Intercropping 803 65 1. indigenous fruit trees in South Africa.

One greenhouse system in Taiwan had 26 crops in 4 years with high inputs of fertilizers and manures (Chang. on average.4 t C ha−1 yr−1 (table 3. to plantations.687 825 2.933 56 Crop-to-forest 528 −80 1.580 1. agriculture. emphasis should be placed on maximizing the use of available land by planting high-yielding tree species.488 14 Latin America Pasture-to-plantation 1. The growing of plantations on former agricultural land sequestered on average an additional 0. average. In any afforestation project. more C is sequestered when the former land use is pasture (about 1. The highest soil carbon sequestration rate for land-use change observed in this review was for intensive vegetable production in Asia (2. The establishment of pasture on cultivated land sequesters 1. and CARBON SEQUESTRATION IN AGRICULTURAL SOILS .094 158 Crop-to–grassland 302 −36 640 35 Exclusion or reduction in grazing 502 126 877 39 Restoration of wetlands 471 1 Annual-to-perennial 1. the conversion of native grasslands including savannahs.6 t C ha−1 yr−1). 2000).169 315 2.36 CH A PTER 3 — META -A NA LY S ES OF SOIL CA R B ON SEQU ES TR ATION TABLE 3.309 60 Asia Crop-to-forest Crop-to-plantation 878 662 1.8: Land-Use Changes and Soil Carbon Sequestration Rates (kg C ha−1 yr−1) PRACTICE MEAN LOWER 95 PERCENT CONFIDENCE INTERVAL OF MEAN UPPER 95 PERCENT CONFIDENCE INTERVAL OF MEAN NUMBER OF ESTIMATES Africa Crop-to-forest Pasture improvement 1. resulted in a net loss of soil carbon of 0.116 −32 2. an impact also observed in some studies of savannas in Brazil (Lilienfein et al. and other land uses in the continent. 2010).1 t C ha−1 yr−1. The species may be similar or mixed in a manner that will generate the highest yield and biodiversity. However. Converting grasslands to plantations in the Pampas region results in acidification of soils (Jobbagy and Jackson 2003).392 36 Intensive vegetables and specialty crops 2. Other studies have suggested that grassland soils may not accumulate carbon once forested and that some humid soils may even lose carbon (Paruelo et al. conversion of cultivated lands to secondary forests sequestered more than 1 t C ha−1 yr−1 in Africa.024 53 Grassland–to-plantation −406 −842 32 32 Exclusion or reduction in grazing Crop-to-pasture Annual-to-perennial Pasture improvement 172 −393 737 30 1. In Latin America.9 t C ha−1 yr−1 in Asia and Latin America—a value comparable to that for secondary forests.8).706 37 799 469 1. This is in sharp contrast to findings for conversion of pastures to forest or plantation.2 t C ha−1 yr−1 in Latin America). The Global Partnership on Forest Landscape Restoration estimates that over 400 Mha of degraded forest landscapes offer opportunities for restoring or enhancing the functionality mosaic landscapes of forest.163 619 1. which are frequently grazed.135 59 Pasture-to-forest 362 −32 756 62 Crop-to-plantation 893 299 1. Chung.004 615 1.129 32 932 554 1.226 3.549 13 Source: This study.265 7 526 239 812 13 1.

respectively. ƒ increases water holding capacity of the soil. ƒ increases microbial biomass and activity. 2011).7 t C ha−1 yr−1 in Africa and Latin America. the differences from estimates from field or agroforestry settings were not statistically significant. has been experimented with for high-value crops in arecanut agroforestry systems (Bhat and Sujatha 2009). ƒ increase water use efficiency by increasing infiltration and reducing runoff. As a soil amendment. Its application has gained recognition in the last few years for both climate change mitigation and soil improvement. sequesters about 0. 2010c). Biochar is a key ingredient in the formation of anthropogenic Amazonian dark earth (soils). for example. productive grasses) Y N Y 799 Pasture to plantation Y Y (N) 1169 Include trees (silvopasture) (N) Y Y 1167 Pasture to forest Y N (N) 362 Excluding grazing (N) N N Grassland to plantation N Y (N) Crop to grassland Y N Y PRACTICE EFFECT Source: This study. ƒ reduce soil and nutrient losses in runoff. while another looked at growing vanilla orchids under different organic manure and mulch combinations in an agroforestry setting (Sujatha and Bhat 2010).2 t C ha−1 yr−1 in Asia and Latin America. the thermal decomposition of biomass under limited oxygen supply and at temperatures below 700°C. An efficient grazing system TABLE 3. Fertigation.9 to aid comparison. manages stocking rates. biochar sequestered carbon the most (table 3. Wang 2008). Although intensified cultivation in greenhouses produced the highest average rates of soil carbon sequestration. These different practices are summarized in table 3. Grazing management helps to ƒ maintain a healthy and productive pasture.5 and 0. and ƒ adds nutrients and improves uptake of applied fertilizers. ƒ maintain higher amounts of soil organic matter and rapid cycling of nutrients. biochar Grazing management. The climate mitigation benefit of biochar lies in the fact that it decomposes more slowly and stabilizes biomass carbon. recognizing that there is not always a clear boundary between categories of effects. encourages more uniform use of paddocks.8 and 1. Grazing management and pasture improvement should be integrated for optimal benefits. Biochar and Other Soil Amendments Of the soil amendments studied. respectively. Increases in soil organic carbon under these high-input systems are likewise rapid (Bhat and Sujatha 2009).9: Summary of Observed Rates of Soil Carbon Sequestration (kg C ha−1 yr−1) as a Result of Land-Use Changes and Other Practices Relevant to Livestock Management GRASS PLANTED TREES PLANTED GRAZING AFRICA Pasture improvement (perennial. Note: Letters in parentheses indicate typical but not absolute conditions. EC O N O M I C A N D S E CT OR WORK ASIA LATIN AMERICA 1687 502 172 −406 302 . and ƒ increases mycorrhizal abundance linked to enhanced agronomic efficiency and yield. Livestock grazing is relevant to many different land-use and agricultural practices. One repeated-sampling design study in India. Biochar is produced by pyrolysis.ANALYSE S OF SOIL CARBON SEQUES TR ATION uses the appropriate mix of grass or legume species for pasture. Application of biochar also leads to avoided emissions of nitrous oxide and methane. This study looks at livestock management practices from several perspectives. thereby maintaining soil physical and chemical quality. the inclusion of liquid fertilizers as part of a drip irrigation system. the control of animal grazing to sustain productivity and ensure continuous supply of forages to animals.37 C H A P T E R 3 — M E TA. But other systems included farms with organic production using no pesticides or chemical fertilizers (Ge et al.10). Pasture improvement sequestered 0. and adjusts the timing of grazing. documented the consequences of intensive cultivation of high-value medicinals and aromatics in an agroforestry setting (Sujatha et al.

Land emissions are the differences between emissions of nitrous oxides and methane expressed in CO2 equivalents by conventional and improved practices. 2010). A modeling study for Indian rice and wheat suggested that increased irrigation and fertilizer application would increase the carbon efficiency ratio even as net emissions rise (Bhatia et al. Net Mitigation Benefits for Nutrient Management Increases in productivity from nitrogen fertilizers and irrigation need to be considered against increased emission of GHGs from soils as well as energy-related emissions.10: Soil Amendments and Soil Carbon Sequestration Rates (kg C ha−1 yr−1) MEAN LOWER 95 PERCENT CONFIDENCE INTERVAL OF MEAN UPPER 95 PERCENT CONFIDENCE INTERVAL OF MEAN NUMBER OF ESTIMATES 2. Reducing wasteful CARBON SEQUESTRATION IN AGRICULTURAL SOILS . However. In general. Net Climate Change Mitigation Benefits of the Land Management Practices Estimates of the net climate change mitigation benefits of the agricultural land management practices are summarized in figure 3. They estimated a net impact of 4. rice bran. Shang et al.000 times longer than the residence time of most soil organic matter. The estimates were derived by converting carbon sequestration rates from this study to carbon dioxide equivalent by multiplying by 3. 2010).1 t CO2e ha−1 yr−1 above unfertilized controls although in terms of emissions per unit yield fertilization was still beneficial.38 CH A PTER 3 — META -A NA LY S ES OF SOIL CA R B ON SEQU ES TR ATION TABLE 3.5 t CO2e ha−1 yr−1 above unfertilized controls. RodriquezKuhl. to as much as 13. the use of biochar should ensure that crop residues and mulch needed for soil protection are not removed from the field. (2010) calculated full GHG budgets over a 3-year period in a long-term experiment on fertilization in a double rice-cropping system in China. No significant increase in nutrient-holding capacity was observed after the addition of biochar to a coastal plain soil (Novak et al. cocoa husk. sawdust.395 8 114 −287 516 9 Source: This study. Rodriquez-Kuhl. Other studies have also indicated an adverse effect of biochar application on earthworm survival. 2010). 2009).889 6 Sulfur 425 106 743 Lime 39 1 Zinc 53 1 PRACTICE Africa Biochar a Soil amendment Asia Biochar 5 Latin America Biochar Lime 3.67 and also by accounting for land and process emissions. possibly due to increases in soil pH. They found fertilizer plots sequestered 470 kg C ha−1 yr−1 more carbon in soil than controls but that long-term fertilization increased CH4 emissions during flooded rice and increased N2O emissions from drained soils at other times.079 5. and Sommer 2004). and Sommer 2004). a Ash. Shang et al.818 747 6.11. At the same time. It should be noted that as much as 70 to 75 percent of fossil fuel use in the agricultural sector in the tropics is for the production and use of chemical fertilizers (Vlek. research results on biochar’s effect on some soil properties are not consistent. intensification of agricultural production (using more fertilizers) on better lands may make less suitable land available for conversion to grasslands and forests with high soil carbon sequestration potential (Vlek. noted that mixtures of inorganic fertilizer and chemical fertilizers increased net annual greenhouse warming potential even further. while process emissions are those arising from fuel and energy use (Eagle et al.. Fertilizers may make no net contribution to mitigation of climate change if the CO2 emitted to produce and transport them exceeds the soil storage benefit (Schlesinger.237 1.219 3. Biochar can remain resident in the soil approximately 10 to 1.303 1.387 11 569 299 839 15 3.

er till to cro -p re er ps sid en ue n m m ial an a n pa u st age re ur m een in to-f t clu or e in de t st te r e r pa c cr es st rop opp ur e. EC O N O M I C A N D S E CT OR WORK 39 .he cr co gra s op ve zin -to r c g -g ro ra ps im ss pr ov m lan ed a d n an in irri ure in nua clud gat i te lns to e t on ive -pe ree w at ve ren s er ge ni ha ta al b in rve les te rs rc tin r cr op bi opp g -to ofe ing -p r cr lan tiliz op ta er -to tio -fo n r bi est oc ha r m ch e ro ch ta em tio i n ca in l f te er ns til ifi ize ro ca r ta r es tion tio id n di m ue ve u s rs lch ifi e c s no atio co til n ve lag ot rc e he ro rs m ps o pa il a t an st m er ure ur en ra e d cin w imp em g at ro en er v ts h e cr in arv me os t e nt e in s s rcr stin clu lo op g de pe pi tre tre /bar ng e.-to.11: Carbon Dioxide Abatement Rates of the Land Management Practices 12 10 Africa 8 6 4 2 0 18 16 14 Asia 14 12 10 8 6 4 2 0 16 Latin America 12 10 8 6 4 2 0 -2 Source: This study.ing to fo r -p lan est ta ti bi on oc ha r no ica o l fe re int r re rtil sid en d ize ap ue si uce r f pl ica ma y ro d ti tio na tat ll n g io re of em n du m en ce ulc t d.es rie cr i rs op n f af far ield fo m r a es in im lley tat g pr fa ion ov rm ed in fa g ll bi ow oc ha r C H A P T E R 3 — M E TA.tio -t gr n no o-p azin or lant g re ati du on c an c nu ov ed al.ch e im mic pr al ov fe di ed rtili ve irr ze ig r r in sify ati te o ns rot n gr re ify atio as du ro n sla ce ta nd d.ANALYSE S OF SOIL CARBON SEQUES TR ATION FIGURE 3.

4: Crop Harvesting in Mali. Depken. The mitigation potential of improved irrigation is almost offset by land and process emissions. but crossslopes/barriers achieve moderate mitigation impact. respectively. The Biomass Is Smaller Compared to that of Agroforestry Systems Source: Curt Carnemark/World Bank. The conversion from conventional agriculture enhances carbon sink potential as much as 8 times in temperate and 1. PHOTO 3. Adoption of reduced till in these systems was expected to reduce total GHG emissions by 4 to 18 percent for various crops as a result of slower decomposition rates and fuel saving for plowing. Japan.7 percent of the fossil fuel emission budget in China for 2003. but they obviously depend a lot on high levels of inputs as well. The life cycle analysis by Koga.230 kg C ha−1 yr−1 in temperate and subtropical areas. Improved management of compost processes and mulches can reduce non-CO2 emissions (Zeman. Their analyses suggest that greenhouses are a net sink of 1. The GHG mitigation benefits of residue management also require consideration of processes apart from soil carbon sequestration. They found that across 10 provinces.210 and 1. and Tsuruta (2006) of conventional and reduced tillage in intensive cropping systems in Hokkaido. found 43 percent lower CH4 emissions in no-till rice. The net potential of straw return (rather than burning) in China was assessed using a GHG budget model by Lu and et al. CARBON SEQUESTRATION IN AGRICULTURAL SOILS . Wang et al. Sawamoto. Returning straw to fields rather than burning it helps avoid emissions associated with producing synthetic fertilizer as well as CH4 and N2O emissions from burning (Lu et al. the total net mitigation potential at soil saturation was equivalent to just 1. Net Mitigation Benefits of Intensification and Water Management Very intensive systems such as vegetable production under greenhouses can sequester a lot of carbon in the soil. Kobayashi. Net Mitigation Benefits for Residue Management and Tillage The net GHG mitigation potential of residue management has been assessed in a few instances. suggested that soil-derived CO2 emissions accounted for 64 to 76 percent of total GHG emissions. The experimental study by Harada. for example. Key constraints include controlling methane emission from rice paddies. (2011) made one of the few full carbon budgets for a greenhouse system. straw return increased net GHG emissions. and Rich 2002). and Shindo (2007). (2010).3 times in tropical areas. emphasizing the importance of soil management practices. 2010).40 C H A PTER 3 — META -A NA LY S ES OF SOIL CA R B ON SEQU ES TR ATION fertilizer use by ensuring that applied rates do not exceed crop requirements is an important mitigation strategy. in the other provinces.

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The RothC model describes the fate of organic inputs entering the soil environment. BIO. the undergoing decomposition within the soil biomass to form a number of carbon pools. resistant plant material (RPM). BIO. The proportion that is converted to CO2 and to BIO plus HUM is primarily determined by the clay content of the soil. and an estimate of the decomposability of the incoming organic FIGURE 4.1: Representation of the RothC Model Organic inputs RPM IOM DPM HUM HUM CO2 BIO BIO CO2 BIO HUM CO2 Source: This study. Subsequent further decomposition of the BIO and HUM produces more CO2. The pools have different susceptibilities to decomposition.1 43 ECOSYSTEM SIMULATION MODELING OF SOIL CARBON SEQUESTRATION MODEL DESCRIPTION The RothC model (Coleman and Jenkinson 2008) was used to project the amount of soil carbon sequestered by different land management practices up to 2035. and inert organic matter (IOM). clay content of the soil. average monthly mean air temperature (in degrees Celsius). BIO = microbial biomass. EC O N O M I C A N D S E CT OR WORK . and HUM. Note: DPM = decomposable plant material. humified organic matter (HUM). One of the main advantages of the RothC model is its requirement of a few. The required inputs are monthly rainfall. easily obtainable inputs to estimate soil carbon. HUM = humified organic matter. Both DPM and RPM decompose to form CO2. monthly open pan evaporation.1). and HUM. IOM = inert organic matter. microbial biomass (BIO). ranging from highly labile to inert materials. The pools include easily decomposable plant material (DPM). RPM = resistant plant material. and the release of CO2. which is highly resistant to microbial decomposition (figure 4.C H A P T E R 4 — E C O SYST E M SIMUL AT ION MODE L ING OF S OIL CA R B ON SEQUES TR ATION Chapter 4: 4.

k is the yearly decomposition rate constant for that particular compartment.1).org/agriculture/seed/cropcalendar/welcome. TABLE 4.1: Spatial Datasets Used in the Study DATA PURPOSE REFERENCES Clay content. Food and Agriculture Organization of the United Nations. a is the rate-modifying factor for temperature. 2009: http://faostat. 2009. root biomass.0786%clay). World-wide Agro Climatic Data Base.60e−0. Y = Y0(1 − e−abckt).67(1.fao. [1] where Y0 is the initial amount of carbon in the particular pool. [2] The global soil carbon mitigation potential due to the adoption of sustainable land management practices was modeled to a depth of 30 cm using the following relationship: Cs = A × f.org/geonetwork/srv/en/metadata. sorghum. and t = ¹⁄¹² is to scale k into monthly values. and wheat) occupying more than 70 percent of the global agricultural area were estimated within a geographical information system and used for modeling. Department of Geography. Harmonized World Soil Database (version 1. Austria. A is the activity data or land area (in ha) where a given sustainable land management practice was adopted. The model has been validated across the agro-ecological zones of the world and has been used for many subnational and national GHG inventories. The RothC model also adjusts for clay content by altering the partitioning between evolved CO2 and soil C x = 1. maize. Department of Geography. Food and Agriculture Organization of the United Nations livestock data for Africa. The activity data (global cropland area) were derived from available spatial datasets (table 4.show Sustainability and the Global Environment Global Agro-Ecological Zones Stratification of Africa Center for Sustainability and the Global Environment.do Direct manure/composted manure input data Carbon input for modeling Global Fertilizer and Manure Application Rates. McGill University. Equations for calculating each of these factors can be found in Coleman and Jenkinson (2008).fao.aspx#ancor Harvested area (ha) of selected crops and crop yield (t/ha/year) data Carbon input for modeling Harvested area and yields of selected crops. CARBON SEQUESTRATION IN AGRICULTURAL SOILS . University of Wisconsin Source: This study.44 CHAP T E R 4 — EC OSY S TEM SIMULATION MOD ELING OF S OIL CA R B ON SEQU ES TR ATION material referred to as the DPM/RPM ratio (Coleman and Jenkinson 2008). and f the emission factor is the sequestered carbon in t C ha−1 yr−1. initial soil carbon content RothC model parameterization Harmonized World Soil Database v 1. Rome.iiasa. [3] where Cs is the change in soil organic carbon as a result of adoption. Environment and Natural Resources Service— Agrometerology Group Crop calendar RothC model parameterization.1).ac. The harvested areas of eight major crops (barley. McGill University Carbon input data for agroforestry and cover crops From several published literature See references Land-use systems Additional data used to estimate land area for which a given technology is applicable FAO Land Use Systems http://www.org/geonetwork/srv/en/main. FAO. rice. Italy and IIASA. others related to the input of carbon such as crop yields. millet. and the proportion of carbon in plant residues are linearly related to the amount of carbon decomposing. pulses. Harvested area and Yields of 175 crops (M3-Crops Data).fao. b is the ratemodifying factor for soil moisture.fao. http://www.html Temperature and precipitation RothC model parameterization FAOCLIM 2. decomposition rates (BIO plus HUM) pools formed during decomposition using the following exponential equation: The amount of carbon (Y) that decomposes from an active pool in a given month can be represented by an exponential decay function of the form where x is the ratio CO2/(BIO + HUM) and BIO and HUM are the corresponding biomass and humic pools formed initially as incoming plant materials. Land Use and the Global Environment. modeling FAO Crop Calendar—a crop production information tool for decisionmaking (FAO 2010): http://www. Laxenburg. Navin Ramankutty. c is the rate-modifying factor for soil cover.org/site/569/default.at/Research/LUC/External-World-soildatabase/HTML/index.home http://www. While the above factors contribute exponentially to the soil carbon remaining at the end of each month.1: FAO/IIASA/ISRIC/ISSCAS/JRC.85 + 1. Land Use and the Global Environment. soybean.

while in Africa. the most dominant cropping systems were identified from the literature. For example. cowpea. different fractions of retained residues (i.44 was set for modeling sustainable land management scenarios except for agroforestry. tillage management. most of the farming systems in North America already leave the residues on the field. FIGURE 4. ƒ The typical land management practices associated with the cropping systems. For each stratum and region. Crop yields and manure were converted into organic residues as model inputs using IPCC standard equations (IPCC.1. precipitation. coppice and improved fallow. A detailed description of the scenarios for Africa is provided in Appendix 4. Africa was classified into four agroecological zones using procedures similar to the global cropland extent (Figure 4.2). mixed smallholder farming systems are the dominant system in Africa. and groundnut as cover crops. and maize-soybeans systems are dominant in several parts of South America. cropping systems in South Asia are dominated by rice.C H A P T E R 4 — E C O SYST E M SIMUL AT ION MODE L ING OF S OIL CA R B ON SEQUES TR ATION Using cluster analysis. This resulted in 12 distinct clusters (strata) within eight regions (Africa.e. North America. The land management practices include integrated residue and manure management. The specific organic inputs for the land management practice being modeled were set on a monthly basis using crop calendars specific for each stratum. manure management.25 was assumed. the global cropland extent was stratified into mapping units based on temperature. To account for trade-offs between mulch residues and livestock and fuel biomass. agroforestry. and integrated fertility management were modeled. Central America.do) to model carbon sequestration under various levels of organic inputs for Africa. The choice of the suitable mitigation scenarios for each world region was guided by the following baseline considerations: ƒ The most dominant cropping systems in a specific region. EC O N O M I C A N D S E CT OR WORK 45 . 2006). Russia. As a result.org/agriculture/seed/ cropcalendar/welcome. A detailed description of the baseline and mitigation scenarios is provided in Appendix 4. A summary of the farming systems is given in Appendix 4. 50 percent. Asia. 25 percent. Oceania.2: The 12 Strata Used for Ecosystem Simulation Modeling Source: This study. a common practice is to burn or remove the residues from the field. For instance. The study also took advantage of the recently released crop calendar for Africa (http://www. land rehabilitation. and South America) (Figure 4. agroforestry systems including perennial crops. and 75 percent) were modeled..1.fao.3). ƒ Documented impact of agricultural land management practices on carbon sequestration (see Chapter 3). and clay content. where a ratio of 0. residue management. Europe. A standard DPM/RPM ratio of 1.2. and cropping systems involving mucuna.

000 land management scenarios carefully chosen to reflect situations typically encountered in agricultural projects.3.46 CHAP T E R 4 — EC OSY S TEM SIMULATION MOD ELING OF S OIL CA R B ON SEQU ES TR ATION FIGURE 4.v-c-s. Users can download data from the Internet database and integrate with other GIS information to estimate soil carbon stock changes for different agricultural projects. 4.org/files/SALM%20Methodolgy%20V5%20 2011_02%20-14_accepted%20SCS.3: Africa Agroecological Zone Uncertainties in model parameters were estimated following the adoption of the Sustainable Agricultural Land Management (SALM) methodology (http://www.pdf).2 RESULTS Soil Carbon Sequestration Internet Tool Modeling results are summarized in an Internet geographical information system (GIS) tool at http://www. The Internet GIS database provides per-ha estimates of soil carbon sequestration under different land management practices for a period of 20 to 25 years (figure 4.4). CARBON SEQUESTRATION IN AGRICULTURAL SOILS .esd. The procedures are provided in Appendix 4. worldbank. Information on carbon sequestration potential of a location can be derived by point-and-click or by searching using place name.org/SoilCarbonSequestration/.org/ sites/v-c-s. The tool includes over 4.

its estimates markedly suffer from lack of good resolution spatial data of no-tillage adopting areas. Middle America is predicted to experience the next highest loss due to depletion of crop residues in virtually all its cropping systems (25 to 37 t C ha−1).08 to 1.C H A P T E R 4 — E C O SYST E M SIMUL AT ION MODE L ING OF S OIL CA R B ON SEQUES TR ATION FIGURE 4.02 to 13 t C ha−1). 47 . while the highest for maize residue (7 to 12 t C ha−1) are predicted for Asia. The spatial patterns of composted and direct manure are similar because both models are based on frequency of livestock. The cumulative C loss is around 15 to 20 t C ha−1 for all cropping systems in Asia. Carbon sequestration potential of the land management practices is in the order of agroforestry > cover crops > manure > crop residues > no-tillage. In Asia.esd.3 t C ha−1). while Russia has the least (less than 0. cumulative carbon sequestration by 2030 varies from 0. EC O N O M I C A N D S E CT OR WORK Figure 4. and suitability of certain tree species for bioenergy. while the highest was recorded for Asia (1 Gigaton). respectively) were observed for North America.6 reveals differences in the predicted spatial pattern of carbon sequestration for the land management practices.5 Million tons (Mt) C for soybean to 37 Mt C for maize (figure 4. Agroforestry is also vital for the restoration of marginal and degraded lands. pulses.4: A Screen Shot of the Soil Carbon Internet Database Source: http://www. The highest cumulative C loss under the low input scenario occurs under rice and pulses for Africa (20 t C ha−1).04 to 14 t C ha−1 versus 0. under pulses for South America (26 t C ha−1). The loss is highest for Russia under wheat. High sequestration rates are generally observed in the Guinea savannah areas in Africa for most of the practices.5). The highest cumulative sequestration for green manure (6 to 10 t C ha−1) are predicted for Europe and North America.org/SoilCarbonSequestration/. The highest sequestration potentials for direct and composted manure (550 and 587 Mt. and under millet for Europe (23 t C ha−1).2). The lowest amount of sequestered carbon from cover crops was recorded for Middle America (15 Mt). Carbon Sequestration Maps Soil Carbon Sequestration Under Different Land Management Practices Carbon sequestration through residue management depends much on the land area devoted to a given crop (table 4. Soil Carbon Loss Under Low Input Baseline Scenario The predicted cumulative C loss by 2030 varies for different cropping systems and regions of the world. increased income through production of indigenous fruit trees. No-tillage sequesters least (0. rice. The highest emphasis should be placed on agroforestry systems because of the diverse benefits they provide including compatibility of some tree species with crops and livestock production. Composted manure sequesters slightly higher than direct manure (0. Agroforestry by far has the highest sequestration potentials for all world regions. the sequestered carbon varies from 10 Mt for millet to 517 Mt for rice. The time-averaged above-ground biomass of trees is relatively large compared to crops.worldbank. Based on the assumption of 50 percent residue retention.2 Mt). and barley (35 to 40 t C ha−1) where the drive to exploit minerals and other natural resources has spread agriculture to unproductive soils and low fertilizer use has led to a sharp decrease in soil fertility.

5: Cumulative Soil Carbon Loss by 2030 Assuming 15 Percent Residue Retention (t ha−1) Under Different Cropping Systems Wheat 0 Middle South North Russia America America America Europe Asia Africa Oceania 0 –5 –5 –10 –10 –15 Soybean Africa Oceania –15 –20 –20 –25 –30 –25 –35 –30 –40 –35 –45 –40 0 Middle North South America America Europe America Asia Middle America South North America America Sorghum Asia Africa Rice Oceania 0 Middle South North Russia America Africa Europe America Asia America Oceania –5 –5 –10 –10 –15 –15 –20 –25 –20 –30 –25 –35 –40 –30 Millet Europe Asia North America Middle South America Africa America Asia Africa 0 North Maize Europe America Oceania 0 –5 –5 –10 –15 –10 –20 –15 –25 –30 –20 –35 –25 –40 Pulses 0 Middle North South Russia America America AmericaEurope Africa Asia Oceania –5 –10 Barley 0 Middle South North Russia America AmericaEurope America Asia Africa Oceania –5 –10 –15 –15 –20 –25 –20 –30 –30 –35 –40 –35 –45 –45 –25 –40 Source: This study. CARBON SEQUESTRATION IN AGRICULTURAL SOILS .48 CHAP T E R 4 — EC OSY S TEM SIMULATION MOD ELING OF S OIL CA R B ON SEQU ES TR ATION FIGURE 4.

000 Kilometers 0 Non Tillage Composted Manure Direct Manuring Residue Management.341 5.000 12.000 9.500 3.916 – 6.552 6.799 3.563 – 3.000 6.000 6.014 – 3.439 – 6.479 3.743 0 1.339 – 12.000 Kilometers .976 6. Maize Source: This study. EC O N O M I C A N D S E CT OR WORK 1.000 9.859 4.342 – 5.338 9.6: Predicted Cumulative C Sequestration for Different Land Management Practices by 2030 Green Manuring Agroforestry 2030 2030 Tons per Hectare Tons per Hectare 2.744 – 9.000 12.49 C H A P T E R 4 — E C O SYST E M SIMUL AT ION MODE L ING OF S OIL CA R B ON SEQUES TR ATION FIGURE 4.438 12.915 3.860 – 23.500 3.553 – 4.480 – 9.

657 9. CARBON SEQUESTRATION IN AGRICULTURAL SOILS .193 48.966 20.50 CHAP T E R 4 — EC OSY S TEM SIMULATION MOD ELING OF S OIL CA R B ON SEQU ES TR ATION TABLE 4.131 136.218 0. K. Rothamsted Research.995 Rice 17.556 2. Tanabe.098 Composted manure 427. Agriculture.252 549.562 Soybean 0.664 32.524 35.504 360.120 34.402 772. and K..rothamsted.495 Source: This study. Buendia.279 33.233 Wheat No-tillage Agroforestry 1.721 1309.637 3.082 14.843 Sorghum 21.763 33. L.064 57.557 7.907 18. and Other Land Uses.558 1.608 727. A Model for the Turnover of Carbon in Soil: Model Description and Windows Users Guide. REFERENCES Coleman. Forestry. and Jenkinson. Institute for Global Environmental Strategies. T.229 19. “Volume 4. Miwa.101 203. K.731 4.993 Pulses 13.2: Modeled Cumulative Soil Carbon Sequestration Potential by 2030 (Mt C) Under Different Land Management Practices AFRICA ASIA EUROPE MIDDLE AMERICA NORTH AMERICA OCEANIA RUSSIA SOUTH AMERICA Residue management Barley 7.080 20.359 Maize 37.uk/aen/carbon/mod26_3_ win.494 11.ac.574 Millet 10. S.281 209.209 Cover crops 513.3.106 5.434 803.” in 2006 IPCC Guidelines for National Greenhouse Gas Inventories. UK. Intergovernmental Panel on Climate Change.pdf.460 586.2008 ROTHC-26.771 516.740 0. Ngara. Available online at http://www. H.700 0. 2006.128 0.237 1009.361 81.415 Direct manure 400. Harpenden. Japan.898 16. S. ed.511 2416.890 478. D.727 632.703 23.868 210. Eggleston.

The width of the column is the amount of GHG mitigated by the land management practice. refer to government support toward the implementation of land management practices. and contribute additional GHGs in the atmosphere.1 ECONOMICS OF SOIL CARBON SEQUESTRATION MARGINAL ABATEMENT COSTS Sustainable land management technologies can generally be deployed at varying costs. Moving along the curve from left to right worsens the cost-effectiveness of the mitigation measures. This suggests that farmers may be reluctant to privately implement land rehabilitation. it both reduces emissions and saves money). The MAC is plotted on the y-axis and GHG abated on the x-axis. Asia. private and public marginal abatement costs were computed. input subsidies. For the private MACs. the marginal benefit of residues for the regions is modest (less than US$50). while the area of each column equals the cost or benefit of adopting the practice. The adoption period was assumed to be 25 years. all possible costs and benefits that would accrue to the farmers were valued at market prices the farmers are likely to face in switching to the practices. Efforts were made to avoid double counting as some of the practices are mutually exclusive.11) were used to scale-up for each continent by multiplying by the suitable areas for each practice within a continent in 2030. with the land management practices ranked against the MAC from the lowest to the highest. The MAC curve can also be used for cost-benefit analysis by comparing the unit mitigation cost with the shadow price of carbon or the cost of purchasing emissions allowance. The public costs. All the land management practices are profitable to the farmer. but to varying degrees (table 5. A MAC curve depicts the relationship between the cost-effectiveness of different land management practices vis-à-vis the amount of GHG abated. Negative MACs indicate that a land management practice is self-financing (that is. With the exception of Asia. In this study. Afforestation and pasture establishment on degraded land with relatively high mitigation potentials are modestly profitable. The marginal benefit of no-tillage is greater than US$100 per tonne of carbon dioxide mitigated for the three regions.1 also reveals the inherent trade-off between the profitability of the land management practices and their mitigation potentials. increase farmers’ vulnerability. the time carbon sequestration reaches saturation for most of the land management technologies.51 C H A P T E R 5 — E C O NOMICS OF SOIL CARBON SE QUESTR ATION Chapter 5: 5. The costeffectiveness of the land management practices in mitigating climate change has been evaluated using the marginal abatement cost (MAC) curve. Such analysis helps in identifying potential mitigation pathways for a given context. Afforestation and grassland rehabilitation cost governments more than $20 per ton of GHG mitigated in Asia and Latin . Alley farming and intercropping also yield relatively high profits in Africa. Computed public costs EC O N O M I C A N D S E CT OR WORK included investments in seeds and seedlings. On the other hand. on the other hand. while positive MACs imply that the land management practice reduces emissions at a cost and thus requires judgment against the cost of inaction. Figure 5.1. Without public support to farmers. manure and fertilizer with modest mitigation potential yielded relatively high profits. The MAC curve analysis was a quantitative assessment of all possible costs and benefits that would accrue if the various management practices were implemented. The abatement rates of the land management practices (figure 3. extension services. The shapes of the curve are similar across scenarios. poor agricultural land management will intensify land degradation. and Latin America. and other administrative costs. Table 5. The assumptions for estimating the suitable areas for the four IPCC special reports on emission scenarios are described in Appendix 5. The cost-benefit flows were discounted to present value to calculate NPV using a discount rate of 9 percent. creating the need to evaluate their cost-effectiveness. The public costs of all the land management practices are lower than US$20 per ton of GHG mitigated in Africa. so only the curves for the A1b scenario are presented.1).1 shows the MACs for Africa.

400 marginal abatement cost ($/t CO2) –200 marginal abatement cost ($/t CO2) 500 –200 Pasture on degraded land –300 Crop to grassland –400 –500 Improved irrigation –600 –700 Annual to perennial Reduced grazing Manure –800 Residues –900 Fertilizer scenario A1B-Asia cropland scenario A1b-Asia grassland Rainwater harvesting cummulative CO2 abated (Mt yr–1) 0 500 1.000 2.000 1.500 2.000 1.000 0 1.000 0 4. CARBON SEQUESTRATION IN AGRICULTURAL SOILS .000 1.000 1.500 0 1.000 0 –25 Include trees –100 Slope/Barriers marginal abatement cost ($/t CO2) marginal abatement cost ($/t CO2) 0 500 Residues –200 Cover crops Afforestation Inorganic fertilizer –400 Rotation diversification Rainwater harvesting Other soil ammendments Biochar –500 Improved fallow Rotation Intensification Manure Alley cropping Intercropping –300 Tree-crop –50 Water management –75 Grazing management Improved pastures –100 Manure –125 Pasture established degraded land –150 –175 –200 –225 Fertilizer –600 No tillage –250 scenario A1b-Africa cropland scenario A1B-Africa grassland CO2 abated (Mt yr–1) CO2 abated (Mt yr –1) 0 3.200 Crop to plantation Cover crops Rainwater harvesting –1.000 0 –100 Intensive vegetables –400 Biochar –600 Improved irrigation Alley farming –800 Crop to forest Manure Organic soil restoration –1.000 Intensify rotation No tillage Biofertilizer Inorganic fertilizer –1.1: The Private Marginal Abatement Cost Curves CO2 abated (Mt yr –1) 0 500 Mt CO2 abated 1.52 C H A PTER 5 — EC ONOMIC S OF SOIL CA R B ON SEQU ES TR ATION FIGURE 5.500 0 0 100 200 300 400 500 600 700 800 –100 Cover crops Grassland to plantation –800 Pasture to forest Crop to forest Diversify trees Inculde-trees Rainwater harvesting Pasture to plantation Intensify rotation Application of manure Intercropping Biochar –1.600 Residue management Diversify rotation marginal abatement cost ($/t CO2) marginal abatement cost ($/t CO2) 0 –200 Pasture improvement –300 Rainwater harvesting –400 Manure Annual to perennial –500 –600 –700 Pasture on degraded land Reduced grazing No tillage Improved irrigation scenario A1b-Latin America cropland Improved irrigation scenario A1b–Latin America grassland Source: This study.000 cummulative CO2 abated (Mt yr–1) 1.500 2.

and rotation diversification in Latin America (US$30. inorganic fertilizer in Asia (US$154.to-plantation. cover crops. residues. while in Latin America. improved irrigation. pasture on degraded land. alley farming Asia Intensify rotation. America (table 5. manure.3 Gt CO2-eq for Latin America to 7.2 indicates that all the land management practices generate benefits to the farmers. biochar. while the lowest total public cost was for terracing in Africa (US$18.7 million). rainwater harvesting No-tillage. organic soil restoration.2). crop-to–grassland Include trees. annual-to-perennial grass.53 C H A P T E R 5 — E C O NOMICS OF SOIL CARBON SE QUESTR ATION TABLE 5. improved irrigation Residues. biofertilizer application. intensify rotation. diversify rotation. The total mitigation potential varies from 2. rotation intensification. as afforestation tends to take land out of production for a significant period of time.7 billion). cover crops. grazing management Improved irrigation. grazing management. annual-to-perennial grass. with the implication that in the absence of countervailing policies. intensify rotation. crop-to-plantation. diversify trees. residues. include trees Source: This study.1 million). include trees. intercropping. pasture to plantation. terracing. provides synergy between profitability and increased soil carbon sequestration. Figure 5. pasture establishment on degraded land Asia Residues. rotation. Private benefits that motivate decisions often fall short of social costs. no-tillage. improved irrigation. GHGs from poor land management will continue to accumulate in the atmosphere.7 million). rotation diversification. afforestation. other soil amendments. inorganic fertilizer. afforestation. and reduced GHG emissions. rainwater harvesting. and organic soil restoration also display relatively high costs in Asia. 5. rainwater harvesting. no-tillage. diversify rotation. afforestation. slope barriers. rainwater harvesting.5 billion).3). grazing management. Intensive vegetable production. biochar Grassland–to-plantation. cover crops. pasture to forest. The total cost for afforestation was highest for Africa (US$2. intensify rotation. Asia (US$16. pasture improvement Pasture on degraded land No-tillage.8 billion). pasture improvement. biochar. alley farming. improved fallows. but at varying costs to the public. include trees. other soil amendments. intercropping. intercropping. For instance. pasture-to-forest. grazing management.4 trillion in Asia. Total private profits range from US$105 billion in Africa to $1.1: Private Savings of Different Technologies Per Ton of Carbon Dioxide Sequestered LESS THAN US$50 US$51 TO $100 MORE THAN US$100 Africa Cover crops. manure. Conversely. cover crops. grassland–to-plantation. residues. alley farming. afforestation. pasture on degraded lands Manure No tillage. increased resilience. pasture. manure.2: Public Costs of Different Technologies Per Ton of Carbon Dioxide Sequestered LESS THAN US$10 US$10 TO $20 MORE THAN US$20 Africa Tree crop farming. tree crop farming. biochar. biochar Latin America Diversify trees. biofertilizer. organic soil restoration. intercropping. cover crops. grazing management Source: This study. inorganic fertilizer. EC O N O M I C A N D S E CT OR WORK . afforestation. and Latin America (US$5. the growing of crops near existing trees. terracing. rainwater harvesting. afforestation. cropsto-plantation. biofertilizer. the land management practices with the largest costs are mainly those associated with trees. while total public costs range from $20 billion in Africa to $160 billion in Asia. attempts to increase soil carbon storage through afforestation may reduce productivity (profitability). residues. intensive vegetables. intercropping. manure. cross-slope barriers.0 Gt CO2-eq for Asia (table 5. include trees. inorganic fertilizer. manure. annual-to-perennial grass. improved pastures Biochar. TABLE 5. cropland–to–grassland Inorganic fertilizer. pasture establishment on degraded land Latin America No-tillage. rainwater harvesting.2 TRADE-OFFS IN SOIL CARBON SEQUESTRATION Trade-off is inherent in the attempt to achieve the triple wins of food security.

Synergies and trade-offs analyses can therefore help in quantifying the extent of “triple wins” of different land management technologies.54 C H A PTER 5 — EC ONOMIC S OF SOIL CA R B ON SEQU ES TR ATION other soil amendments improved fallow afforestation include trees slope barriers terracing residues rotation diversification rotation intensification cover crops manure alley frming intercropping inorgnic fertilizer no tillage rainwater harvesting intensive vegetables afforestation crop-to-plantation cover crops intensify rotation improved irrigation biofertilizer organic soil restoration include-trees biochar manure no tillage alley frming inorgnic fertilizer rainwater harvesting residue include-trees manure intercropping pasture to plantation afforestation cover crops pasture to forest diversify trees grassland to plantation rainwater harvesting intensify rotation biochar diversify rotation Asia improved irrigation 20 0 –20 –40 –60 –80 –100 –120 –140 –160 residues 50 0 –50 –100 –150 –200 –250 –300 –350 –400 Africa no tillage 4 2 0 –2 –4 –6 –8 –10 –12 –14 –16 tree crop farming FIGURE 5. Forest.3). Intercropping is CARBON SEQUESTRATION IN AGRICULTURAL SOILS . trade-off was analyzed by using two-dimensional graphs to depict relationships between carbon and profitability and between private benefits and public costs.2: Total Private Benefits (Blue) and Public Costs (Red) of Land Management Practices (US$. Notes: The public costs for Africa were adapted from a World Bank study on Nigeria’s Agricultural. In this study. Billion) for the B1 Scenario Latin America Source: This study. The analysis was limited to the Africa dataset. respectively. The public costs for Asia and Latin America were assumed to increase proportionately to the state support for agriculture for China (8 percent) and Brazil (6 percent).3 reveals synergies between profitability and mitigation in two agroforestry systems: intercropping and alley farming (top right quadrant of figure 5. as the graphs for other regions exhibit similar patterns leading to the same conclusions. Figure 5. and Other Land Use sectors where public support for agriculture is 3 percent. Synergies and trade-offs in CSA affect decision making at various levels ranging from the household to the policy levels.

3: Technical Mitigation Potential.8 A1b 2.55 C H A P T E R 5 — E C O NOMICS OF SOIL CARBON SE QUESTR ATION TABLE 5.3 143.6 19.9 B2 2.977 1.8 40.448 105.3: Trade-Offs Between Profitability and Carbon Sequestration of Sustainable Land Management Technologies in Africa profit per tone of carbon dioxide sequestered (US $) 1000 No-tillage Inorganic fertilizer Intercropping 100 Alley farming Manure Cover crops Soil amendments Crop residues Include trees Terracing 10 Rotation intensification Rotation diversification Afforestation Tree crop farming Rainwater harvesting Improved fallow Cross slope barriers 1 0 2 4 6 8 carbon dioxide sequestered (ton per hectare per year) Source: This study.7 A2 6.388 1.678 1.3 B1 5.3 A1b 6.007 1. B2 = a world more divided but more ecologically friendly.097 319.926 120.8 150.310.6 A1b 3. A1b = a world more integrated with a balanced emphasis on all energy sources. BILLION ) Africa B1 3.321 273.9 22.8 A2 3.4 19.425 279.368.4 42.6 B2 7. FIGURE 5.4 B1 2. Private Benefits. A2 = a world more divided and independently operating self-reliant nations.3 A2 3. and Public Costs of the Land Management Technologies by 2030 TECHNICAL POTENTIAL (MILLION TONS CO2-eq) SCENARIO PRIVATE BENEFITS (US$.678 111.5 131.259.505 108.7 B2 3.1 159. EC O N O M I C A N D S E CT OR WORK 10 . Notes: B1 = a world more integrated and more ecologically friendly. BILLION ) PUBLIC COSTS (US$.538 288.224.4 55.8 44.1 Asia Latin America Source: This study.4 20.

104 kg/ha in South Asia. Judicious fertilizer application counters soil nutrient depletion.3 have high carbon sequestration rates but are modestly profitable. preferably leguminous trees or shrubs.4: Relationship between Private Benefits and Public Costs in Africa private benefit (per tonne of carbon dioxide sequestered) 1. above-ground biomass of crop residues and other technologies in the lower left quadrant of figure 5. but with patterns that depend on crop type. so a large amount needs to be applied on relatively small fields. whereas alley farming is growing crops simultaneously in alleys of perennials. and are more sustainable in the long run. Strong public FIGURE 5. input subsidies. They include investments in seeds and seedlings. Manure plays a crucial role in improving fertilizer use efficiency and soil moisture conservation Manure is less profitable than inorganic fertilizer because of the labor costs associated with collecting and processing manure (top left quadrant of figure 5. Yields also increase with manure application and accumulation of soil carbon. but can lead to overall increases in productivity and stability in the long run. Public support that focuses on research. Reversing developing countries’ (especially Africa’s) soil productivity declines cannot be adequately addressed without increased fertilizer use. Public cost refers to government support toward the implementation of land management practices. Also. Farmers apply 9 kg/ha of fertilizer in Africa compared to 86 kg/ha in Latin America. resulting in lower mitigation benefits. Manure also has quite low nutrient content relative to inorganic fertilizers. The low profits suggest that farmers may be reluctant to privately invest in these technologies.4). including trees in croplands. Afforestation.3). the biomass of crop residues does not accumulate easily.000 No-tillage Inorganic fertilizer Intercropping 100 Alley farming Manure Cover crops Terracing Include trees Crop residues Crop rotation 10 Afforestation Tree crop farming Improved fallow Rainwater harvesting Cross slope barriers 1 0 3 5 8 10 13 public cost ($ per tonne of carbon dioxide sequestered) Source: This study. reduces deforestation and expansion of cultivation to marginal areas. and land tenure rather than on input support are generally more effective. The relationship between public costs and private benefits of the land management technologies is shown in figure 5. and increases crop yields. The time-averaged. benefit more farmers.56 C H A PTER 5 — EC ONOMIC S OF SOIL CA R B ON SEQU ES TR ATION growing crops near existing trees. extension services. The relatively high profitability of no-tillage derives primarily from the decrease in production costs after establishment of the system. Technologies that involve significant change in land-use (afforestation and improved fallows) and landscape alteration (terracing and cross-slope barriers) incur high public costs but generate low private benefits (lower right quadrant of figure 5. improved fallow involving the use of fast-growing trees to accelerate soil rehabilitation. and adaptation benefits in agriculture. The pattern of public support is as crucial as the amount of support for full realization of productivity. Both are important strategies for increased productivity and resilience of the farming system. and other administrative costs. It reduces the amount of land available for cultivation in the short run. and 142 kg/ha in Southeast Asia (Kelly 2006). Land management technologies in the lower right quadrant of figure 5. and establishing barriers across sloping areas. CARBON SEQUESTRATION IN AGRICULTURAL SOILS .4. mitigation. Manure systems are also associated with high methane emissions. tends to take land out of production for a significant period of time.3 is relatively small compared to that of agroforestry systems. investments in improved land management. This explains why manure works well for smallscale intensive and high-value vegetable gardening.

environment.3 IMPLICATIONS OF THE TRADE-OFFS IN LAND-USE DECISIONS The trade-offs exhibited by the land management technologies have important implications for land-use decision making. Two examples taken from World Bank (2011c) illustrate the efficacy of the landscape approach. and pollination. respectively). Examples of market-smart subsidies include demonstration packs. and the support helps improve targeting through market-smart subsidies while providing impetus for private sector input development.4. figure 5. erosion was accelerating. The landscape approach provides a framework for the better management of ecosystem services. crop rotation. fresh water cycling. and crowding out of commercial sales. Crop residues. It entails the integrated planning of land. forests. watershed. Morris. These technologies generally have low mitigation potentials. Thus. however. vouchers. and regional scales to ensure synergies are properly captured. Working at the landscape level with an ecosystems approach is useful for addressing food security and rural livelihood issues and in responding to the impacts of climate change and contributing to its mitigation. and loan guarantees (Agwe. and Fernandes 2007). and livestock productivity was falling. pastures were degraded. a pilot project introduced silvopastoral techniques PHOTO 5. cover crops. 5. agriculture.57 C H A P T E R 5 — E C O NOMICS OF SOIL CARBON SE QUESTR ATION involvement in these technologies is justifiable given their relatively high mitigation potentials. and rainwater harvesting with lower profits and also manure and no tillage that generate relatively higher profits require minimal government support (lower left and upper left quadrants of figure 5.4) reflects the use of subsidies in spurring farmers’ access to the technology. carbon storage. fertilizer subsidies are appropriate in situations when the economic benefits exceed costs. The landscape level is the scale at which many ecosystem processes operate and at which interactions among agriculture. such as agricultural productivity. associated with high fiscal costs. matching grants. EC O N O M I C A N D S E CT OR WORK . fisheries. biodiversity protection. It allows trade-offs to be explicitly quantified and addressed through negotiated solutions among various stakeholders. the subsidies help achieve social rather than economic objectives. After several years of intensive grazing in Costa Rica and Nicaragua. and sectors. The relatively high public cost of inorganic fertilizer (top right quadrant. difficult targeting. and water at local. To address these challenges. The first example is the silvopastoral farming systems of Costa Rica and Nicaragua. Sustainable land management interventions should be planned and implemented in a coordinated manner across space. and development objectives are mediated. Fertilizer subsidy is.1: Terracing and Landscape Management in Bhutan Source: Curt Carnemark/World Bank. time.

improving the livelihoods of 2. The techniques have been shown to enhance biodiversity. Revegetation has successfully restored the devastated Loess Plateau to sustainable agricultural production. trees. and reduce methane emissions. when technologies are inconsistent with community rules and traditional practices. these measures not only increased average yields. conservation agriculture. A payment scheme for environmental services—carbon sequestration and biodiversity conservation—was introduced as an additional income stream for livestock production. It is unlikely that any of these interventions alone will be effective in increasing input use. south-south knowledge exchange.5 Mt of CO2-equivalent was accompanied with increases of 22 percent in milk production. improved availability of inputs is a necessary but insufficient condition for adoption of land management practices. and use of cover crops. and impact of these land management technologies. sustaining soil fertility and enhancing carbon sequestration. Beyond these. For instance. Silvopastoral techniques were used to transform degraded lands with monocultures of one grass species into more complex agroforestry systems of different tree species. while biodiversity (measured by the number of bird species and water quality) increased. Ill-defined land ownership may inhibit sustainable land management changes. First.5 POLICY OPTIONS FOR SOIL CARBON SEQUESTRATION Private benefits that drive land-use decisions often fall short of social costs. their adoption faces many socioeconomic and institutional barriers. The commonly cited risk-related barriers to adoption of carbon sequestering technologies in agriculture are permanence. residue management. Careful selection of combinations of demand. However. there are a number of other implementation constraints. requiring training and practical experience of those promoting its adoption. and technical support mechanisms may increase innovation and facilitate adoption of improved land management technologies. and 60 percent in farm income. 38 percent in stocking rate. Behavioral change through education is required to enable changeover to improved land management technologies. 5.and supply-side measures will allow the demand and supply to grow.1). lack of information on the potentials of alternative techniques of farming and limited capacity is a major constraint in many developing countries. leading to the emergence of viable private sector–led input markets. and trees dispersed in pastures. most of the land management technologies require significant up-front expenditure that poor farmers cannot afford. regional platforms.4 SUSTAINABLE LAND MANAGEMENT ADOPTION BARRIERS Despite the fact that improved land management technologies generate private benefits.000 ha between 2001 and 2007. riparian forests. The project encouraged natural regeneration of grasslands. the evolution of farm and family incomes has shown a steady increase. sequester carbon. Agricultural production has changed from generating a narrow range of food and low-value grain commodities to high-value products. scientific research. Factors affecting adoption tend to be more specific to the land management technologies. live fences. their adoption will most likely encounter the resistance of the people. As a result. and additionality (box 5. the nonavailability of inputs in the local markets can be a significant barrier in situations where farmers might want to invest in a technique.58 C H A PTER 5 — EC ONOMIC S OF SOIL CA R B ON SEQU ES TR ATION to 265 farms on 12. thus. Better market prices for crops and other agricultural produce are crucial.and supply-side interventions for facilitating the adoption of sustainable land management inputs.5 million people and securing food supplies in an area where food was sometimes scarce in the past. 5. Table 5. The knowledge base of land management practices at the local level can also be improved through careful targeting of capacity development programs. The last example is one of the world’s largest erosion control programs in China. Fourth.4 suggests that lack of credit and inputs and land tenure problems are by far the most important factors for adoption across the range of technologies. Learning hubs. carbon sequestration may not reach an CARBON SEQUESTRATION IN AGRICULTURAL SOILS . willingness and the ability to work together are crucial for many technologies such as improved irrigation and communal pastures. diffusion. The absence of collective action will hinder successful uptake. Results showed a typical win-win situation: An annual sequestration of 1. It is estimated that as many as 20 million people have benefited from the replication of the Loess Plateau approach throughout China. The methane emission per product kilogram decreased. Replanting and a grazing restriction allowed the perennial vegetation cover to increase from 17 to 34 percent between 1999 and 2004. Last. is highly knowledge intensive. Together with terracing. Second. Third. the farming system involving no-tillage. and shrubs on previously cultivated sloping lands. Secure land rights is a precondition for climate-smart agriculture as it provides incentive for local communities to manage land more sustainably.5 summarizes possible demand. Table 5. leakage. but also significantly lowered their variability.

as such. Additionality is usually calculated as postproject carbon stocks less the forward-looking baseline. Substitution of fossil fuels by bioenergy is a permanent mitigation option. The risk of nonpermanence is lower when the adoption of soil carbon sequestration practices also leads to more profitable farming systems. and less emission generated by the project (Fynn et al. Carbon sequestration only removes carbon from the atmosphere until the maximum capacity of the ecosystem is reached. rather. and verification (MMV) and contract renewal costs need to be borne by the project MMV are not necessary. less deduction for leakage and risk of reversal. These can be based on stock change or average stock change during the period Environmental rigor Rigorous as temporary credits must be replaced when they expire Credits may not equal debits for a given project. which in turn influence farmers’ land-use and management practices. This could be as a result of technology transfer or changes in market conditions that stimulate mitigation activities. Some public policies that can potentially incentivize carbon sequestration include the following: EC O N O M I C A N D S E CT OR WORK 1. and reduction in nitrous oxide and methane emissions are nonsaturating. control of grazing in an area might force herders to move their animals to another location. credits are reduced by formula. positive leakage spillover effects that lead to reduction in emissions outside the project boundary can occur. ex ante discounting. Economic adjustment to meet market demand is the underlying driver Additionality: The concept implies that in order to attract compensation. perpetual accounting may hinder balancing the books at the end of a finite-life project Transaction costs Measurement. Permanence: Permanence refers to the secure retention of newly sequestered carbon. 2007. however. This achieves consistency as long as the system is monitored perpetually Feasibility of implementation Enables up-front payment. 2007). 2010). monitoring. emissions reduction must be in addition to what would have occurred under the business-as-usual scenario. While most occurrence of leakage has a negative effect on project benefits. Note that not all agricultural mitigation options are transient. Macroeconomic policies induce changes in market conditions and prices. not observed changes in carbon MMV are carried out into perpetuity Source: Table synthesized from Murray et al. and additionality can be addressed through temporary crediting. Countries must be prepared to access new and additional finance. Strengthen the capacity of governments to implement climate-smart agriculture. leakage. ex ante discounting may lead to underdebiting or overdebiting of ex post reversal. Storage of carbon in soils is relatively volatile and subject to re-emission into the atmosphere in a subsequent change in land management. For instance. optimal level from a social point of view unless some mechanisms exist to encourage farmers. which may be about 25 years for most land management practices. There is a need to build the technical and institutional . book balancing at the end of the project is also possible Relatively easy to impose discounts on credits if amounts of reversal can be reasonably projected Boosts attractiveness of investment by allowing credits to be earned as soon as they are generated by the project.59 C H A P T E R 5 — E C O NOMICS OF SOIL CARBON SE QUESTR ATION BOX 5. • Leakage: Leakage occurs when a project displaces greenhouse gas emissions outside its boundary. Permanence.1: Risk-Related Barriers to Adoption of Soil Carbon Sequestration Activities • • of leakage. and comprehensive accounting (Murray et al. TEMPORARY CREDITING EX ANTE DISCOUNTING COMPREHENSIVE ACCOUNTING Description Balances debits and credits for finite periods with provision for reversal Accounts for the possibility of future loss by reducing the amount of credit at the onset based on the expectation of reversal Balances debits and credits as they occur in the course of the project.

irrigation. Morris. the real and potential contributions the sector can and does make in terms of sequestering carbon in agricultural biomass and soils were for the most part omitted. small bags for fertilizers) Implement laws that enables farmers to use risk-free collaterals for loans Reduce distribution costs Improve road and rail infrastructure to lower transport costs Provide farmers with risk management tools Improved weather forecasting. progress in incorporating it into the UNFCCC has been slower than many people hoped for. Existing national policies. and Fernandes (2007). Key * = Low importance. *** = High importance. and investment plans should be strengthened to form the basis for scaling-up investments for climate-smart agriculture. and storage systems Empowering farmers by supporting producer organizations Investment in rural education Training farmers in organizational management Improving the resource base so that input use is more profitable Investment in soil and water management and irrigation infrastructure Source: Modified from Agwe. Although the negative impacts of agricultural production in terms of land-use change and GHG emissions were reasonably well covered by the convention. weather-indexed crop insurance Strengthen business finance and risk management Use credit guarantee and innovative insurance schemes Improved quality and dissemination of market information Public and private sector information systems easily accessible to farmers Improve supply chain coordination mechanisms Product grades and standards Market information systems to reduce information costs Protecting farmers against low and volatile output prices Investment in measures to reduce production variability such as drought-tolerant crops.5: Interventions for Facilitating Increased Input Use DEMAND-SIDE INTERVENTIONS SUPPLY-SIDE INTERVENTIONS Strengthen soil-crop research and extension Support to public agencies Public-private partnership On-farm trials and demonstrations Reduce input sourcing costs Lowering trade barriers to increase national and regional market size Improve farmers’ ability to purchase inputs Improve access to credits Phased and incremental use (e. 2. 2011..4: Relative Importance of Different Factors for Adopting Improved Land Management Practices LAND MANAGEMENT TECHNOLOGY INPUTS/ CREDITS MARKET ACCESS TRAINING/ EDUCATION LAND TENURE RESEARCH INFRASTRUCTURE Inorganic fertilizer *** ** ** ** * ** Manure ** ** * ** * ** Conservation agriculture ** ** *** ** ** * Rainwater harvesting ** ** ** *** ** ** Cross-slope barriers ** * ** ** ** * Improved fallows ** * * *** ** * Grazing management *** *** ** *** ** * Source: Synthesized from Liniger et al.g. capacity of government ministries to implement climate-smart agriculture programs. deep-rooted crops. Redressing this omission promises to foster a more balanced perspective in which food security is not necessarily at odds with climate change adaptation CARBON SEQUESTRATION IN AGRICULTURAL SOILS .60 C H A PTER 5 — EC ONOMIC S OF SOIL CA R B ON SEQU ES TR ATION TABLE 5. ** = Moderate importance. strategies. TABLE 5. Global cooperative agreement. Readiness for carbon sequestration and climate-smart agriculture can be achieved through improved extension services and training in relevant land management technologies for different locales. Given the tremendous significance that agriculture has for the global climate.

However. Nationally owned climate-smart EC O N O M I C A N D S E CT OR WORK agricultural policies and action frameworks will increase the adoption of sustainable land management practices.. C. 2011. L. establishing tree plantations. Climate-Smart Agriculture—A Call to Action. P. Bundling agricultural credit and insurance together and providing different forms of risk management. such as indexbased weather insurance or weather derivatives. R. 2007. World Bank. E. A blend of public. R. public investment is only one sphere. As a result. Agriculture and Rural Development Discussion Paper 23. Alvarez. Oldfield. Schohr. Factors Affecting Demand for Fertilizer in SubSaharan Africa. At the 17th Conference of Parties to the UNFCCC in Durban. T. A. World Overview of Conservation Approaches and Technologies and Food and Agriculture Organization of the United Nations. C. World Bank. finite public resources can be more selectively targeted using the criteria given above—prioritizing technologies that generate no short-term returns and those that most effectively address the barriers that prevent prospective adopters from moving forward..” This is vitally important because agriculture needs to be fully incorporated into adaptation and mitigation strategies. A more practical and thorough picture makes it possible for agriculture to be rewarded for its positive environmental impacts. DC. J. Brown. New York. Integrating sources of climate finance with those that support food security may be one of the most promising ways to deliver climate-smart agriculture with the resources it requires.. and development finance will be required to scale-up improved land management practices. E. Morris. REFERENCES Agwe.. L. South Africa. Raise the level of national investment in agriculture. Rangelands: Issues Paper for Protocol Development.. 2007. Sustainable Land Management in Practice—Guidelines and Best Practices for Sub-Saharan Africa. Boost financial support for early action. the international community has recognized the importance of integrating agriculture into the ongoing negotiations on the international climate change regime. V. “Africa’s Growing Soil Fertility Crisis: What Role for Fertilizer?” World Bank Agriculture and Rural Development Note Issue 21 (May): 4 pp. DC. Fynn. Create enabling environments for private sector participation. Liniger. For technologies such as conservation agriculture that require specific machinery inputs.S. and Additionality for Soil Carbon Sequestration Projects. Laca. Public investment can also be used to leverage private investment in areas such as research and development. C. M. Hauert. C.61 C H A P T E R 5 — E C O NOMICS OF SOIL CARBON SE QUESTR ATION and mitigation (an unworkable conflict in which longer term environmental concerns are virtually guaranteed to universally lose out politically to the more immediate concern of food supply). While this may appear a tall order in countries with severe budget constraints..” Climatic Change 80: 127–143. Washington. B. involving the private sector in climatesmart agriculture and sustainable land management is the other. P. T. For technologies that generate significant private returns.. in November. payment for ecosystem services scheme could be used to support farmers and break the adoption barrier.. M. “Economic Consequences of Consideration of Permanence. J. Soil Carbon Sequestration in U. M. There is also the potential for carbon finance to support farmers during the initial period before the trees in agroforestry systems generate an economic return.. T. and to be an integral part of “the solution” as well as part of “the problem.. B.. . H. Murray. private. In some cases. J. 4.. Leakage. and significant up-front costs. 3.. and Wong. Sohngen. the parties asked the UNFCCC Subsidiary Body for Scientific and Technological Advice to explore the possibility of a formal work program on agriculture. M. C. 2011. Kelly.. Kustin. are areas of private investment that can be encouraged through public policy and public-private partnerships. A. This private investment can be targeted to some degree as well. George. R.. 2010. grant funding or loans may be more suitable to overcoming adoption barriers. Washington. A. P.. 5. relatively affordable technologies that generate quick and demonstrable benefits may warrant priority and potentially establish some of the channels through which more sophisticated technologies are dispersed in the future. 2011. J. particularly when government priorities translate clearly into business opportunities and certain areas of investment are looked upon favorably by public officials and institutions. and Gurtner. and Fernandes. Mekdaschi Studer. Environmental Defense Fund. and Ross. Neely. Introducing policies and incentives that provide an enabling environment for private sector investment can increase overall investment. 2006. and in developing improved seeds and seedlings. Particular attention should go to encouraging private financial service providers to tailor instruments that enable farmers who adopt SLM practices to overcome the barriers described above.

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2 18. NUMBER OF ESTIMATES.4 103 3 20 100 187 4.63 AP P E N D I X A — FA RMING P RACT ICE E F F E CT.5 12 100 6 24 Agroforestry Trees/forest 125 Intercropping 14 Alley farming 46 Tree-crop farming 44 Land-use changes Afforestation 16 Grazing pasture 32 Cropping intensity 55 Soil management Crop rotation 49 Improved fallow 71 Natural fallow 68 Water management Water/rain harvesting 33 Slope/barriers 22 Terracing 15 44 Others 100 Biochar 11 11 1.5 10 100 56 2. A ND FEATUR E IN LA ND MA NA GEMENT Appendix A: FARMING PRACTICE EFFECT. NUMB ER OF ESTIMATES .3 15 100 184 4 15 100 185 6 22 100 2.8 Soil amendment 15 15 1.4 10 .8 EC O N O M I C A N D S E CT OR WORK 7. AND FEATURE IN LAND MANAGEMENT PRACTICES Africa LAND MANAGEMENT PRACTICES NUMBER OF ESTIMATES Nutrient management Chemical fertilizer 30 Animal manure 30 Tillage and residue management No tillage 108 Residues 46 Mulches Cover crops SUBTOTALS MEAN DURATION MEAN DEPTH EXPERIMENTAL DESIGN (%) 60 8.

64 AP P E NDIX A — FARMING P RACT ICE EFFECT.6 18 100 14.3 27 64 150 14.0 26 97 328 9. A ND FEATUR E IN LA ND MA NA GEM ENT Asia PRACTICES NUMBER OF ESTIMATES Nutrient management Application of fertilizer 297 Application of manure 146 Tillage and residue management Reduced or no till 189 Application of mulches 53 Cover crops 38 Agroforestry Inclusion of trees 58 Intercropping 17 Intensification Intensive vegetables 57 Annual-to-perennial 36 Intensify rotation 43 Improved irrigation 10 158 Crop-to-grassland 35 Reduced grazing 39 Other amendments and practices 443 17.5 29 5 25 8. NUMB ER OF ESTIMATES .3 20 99 75 8.4 49 34 292 18.5 29 68 6 Bio-inoculant 3 Gypsum 8 Sulfur 5 Lime 2 Zinc 1 TOTAL EXPERIMENTAL DESIGN (%) 60 Crop-to-plantation Biochar MEAN DEPTH (cm) 4 Land-use change Crop-to-forest MEAN DURATION (yr) 48 Return of crop residues to field Rain harvest SUBTOTALS CARBON SEQUESTRATION IN AGRICULTURAL SOILS .

5 33.2 29.8 90 56 8.0 38. EC O N O M I C A N D S E CT OR WORK . NUMB ER OF ESTIMATES .5 5 17 5.1 82 931 12.0 64 257 19.6 28.5 61 13 Land-use change Crop-to-pasture MEAN DEPTH (cm) 43 Diversify trees Annual-to-perennial MEAN DURATION (yr) 249 Return of crop residues to field Inclusion of trees SUBTOTALS 7 30 Other amendments Biochar 8 Lime 9 TOTAL Source: This study. A ND FEATUR E IN LA ND MA NA GEMENT Latin America PRACTICES NUMBER OF ESTIMATES Nutrient management Application of fertilizer 74 Application of manure 25 Tillage and residue management Reduce or no till 56 Application of mulches 16 Cover crops 33 Graze residues 10 Agroforestry 6 Intercropping 7 Intensification Intensify rotation 25 Diversify rotation 43 Improved irrigation 34 Improved pasture 15 Improved fallow 8 Pasture-to-forest 62 Crop-to-forest 59 Pasture-to-plantation 53 Grassland-to-plantation 32 Crop-to-plantation 14 Reduced or excluded grazing EXPERIMENTAL DESIGN (%) 99 9.65 AP P E N D I X A — FA RMING P RACT ICE E F F E CT.1 24.9 21.7 17.2 92 364 8.3 61 138 15.

.

assuming a conventional management of 15 percent of residues left on the ground after harvesting. However. the C input per ha for each kg N was calculated based on Food and Agriculture Organization of the United Nations (FAOSTAT) numbers of cattle. the 50th percentile. 67 . Similar to the procedure for residue calculation. goats. ƒ initial carbon mass of resistant plant material (RPM). manure management can be classified into direct manure application and application of composted manure. the models were run in reverse mode to estimate ƒ initial carbon mass of decomposable plant material (DPM). who estimated plant biomass requirements to maintain soil organic matter range between 3. and humid ecosystems. Further. sheep. and poultry for each region. subhumid. The calculation of residues inputs from the crops was based on the global crop yield data. respectively. B. ƒ initial carbon mass of slow decomposing biomass (BIO-S). All models were run to equilibrium state increasing the organic inputs in 0. and ƒ initial carbon mass of soil. ƒ initial carbon mass of humified organic matter (HUM).m. Manure Management For each stratum. and 14 t d. Two scenarios were considered with regard to increased productivity as a result of integrated nutrient management practices: A shift from low productivity to medium productivity (25 percentile to 50 percentile of crop yields in a specific stratum) and a shift from medium to high productivity (50 percentile to 75 percentile of crop yields in a specific stratum). one low organic input baseline scenario was modeled for each crop and crop area. ƒ initial carbon mass of fast decomposing biomass (BIO-F).1 GENERAL SCENARIO ASSUMPTIONS AND APPLICATION FOR WORLD REGIONS BASELINE SCENARIO Using the initial soil carbon stocks (in t C/ha) from the Harmonized World Soil Database. 7. For instance. respectively. The average fresh yield was converted to amount of residues produced on the basis of IPCC equations (IPCC 2006). per ha per year for semi-arid. a farmer in a specific stratum whose current maize yield is within the 25th percentile may be able to increase the yields to within the 75th percentile due to increased inorganic fertilizer application. the raw manure and composted manure model inputs in tC/ha were estimated by applying IPCC factors to the average amount of farm animals per ha (IPCC 2006). it served as a proxy to consider increase of yields over time due to improved management practices including the increase in application of inorganic fertilizer (integrated nutrient management).AP P E N D I X B — G E NE RAL SCE NARIO ASSUMP T IONS A ND A PPLICATION FOR WORLD REGIONS Appendix B: B.1 t C steps until the initial carbon stock represented the equilibrium of the specific soil in each stratum. pigs. and the 75th percentile of the yields of a specific crop in one stratum to assess the opportunity of adapting the residue management to local situations.5. the inputs were in line with observations made by Young (1997). Therefore.2 GLOBAL MITIGATION SCENARIOS Residue and Integrated Nutrient Management This scenario implies additional residue inputs due to crop management improvement. Crop yields were grouped into three bins representing the 25th percentile. The global data estimated manure application in kg per ha of nitrogen. EC O N O M I C A N D S E CT OR WORK Generally. The crop yields for each stratum are presented in Appendix C. The required addition of organic inputs to the soil varied greatly depending on climate parameters and the clay content of the soil.

To reverse this situation. 2005b. agroforestry. B. wheat. and the remaining 50 percent was assumed to be removed as animal feed. the input value for tropical and temperate agroforestry systems averaged 2. increase yields. ƒ In Mexico. the best package of practices for soil carbon sequestration for the region consists of a combination of manure application. and agroforestry were modeled for each of the strata.68 AP P E NDIX B — GENERA L SC ENA RIO A SS UMPTIONS A ND A PPLIC ATION FOR WORLD R EGIONS The amount of manure/composted manure represents the amount of potential manure production and not the amount of manure actually spread on the field in the baseline. a robust average input value was used based on input values from various studies for tropical and temperate climate regions.8 t d. trees on cropland. the use of several varieties of mucuna (Mucuna pruriens) in rotation with maize produced on average 6. Apart from rice. 50 percent residue retention was assumed. and enhance resilience to climate change need to be adopted. either as litter or through pruning and mulching. Compared to green manure/cover crops. and then computing the average value for RothC modeling. In general. In addition.3 APPLICATION TO WORLD REGIONS Africa In Africa. crop yields have remained stagnant for decades due to continuous depletion of soil organic matter over time from unsustainable practices. Take for instance. Asia In many areas.5 t d. sustainable practices such as cover cropping. the most dominant farming system is intensive wetland rice cultivation with or without irrigation. and agroforestry were modeled for each cluster. For each stratum. 2010). Agroforestry and Improved Fallow Agroforestry.8 tC/ha on average (Kaonga and Coleman 2008). of which 0. On average. Based on the literature research. including improved fallow. 2003). Like Africa. the introduction of the mungbean (Vigna radiata) as a grain legume in the short fallow of the wheat-rice system produced a total biomass of 4./ha (Yaqub et al. mixed smallholder farming systems are dominant (soybean.m. and roots and tubers) with currently low input (organic and inorganic). ƒ In Asia.43 C ha−1 was allocated as aboveground input and 1. All mapping units (see page 45) in Africa were considered for the modeling.3 tC/ha and 1. covering a wide range of different agroforestry practices such as alley cropping. fertilizer application. green manuring. water harvesting. Therefore. non-N-fixing forage. manure management (direct and composting). Rice is grown in the wet season under dry land farming. and so forth (Oelbermann. Voroney./ha (Eilittä et al. the average manure/composted manure production was calculated for its use in the RothC model. maize.m. manure management (direct and composting). CARBON SEQUESTRATION IN AGRICULTURAL SOILS .44 t C ha−1. and Gordon 2005a. All mapping units in Asia were considered for the modeling. Based on this average conversion. the following: ƒ In Zambia. Improved manure and composted manure application are considered mitigation opportunities for all climatic regions. and residue management.01 C ha−1 as below-ground input. was considered a mitigation potential for all climate regions. Based on this. and grass. the input value for the RothC model concerning improved fallow is found to be similar to that of other agroforestry systems. Green Manure/Cover Crops Green manure is a type of cover crop grown to add organic matter and nutrients to the soil. These values represent the organic input from trees to the soil. Gama-Rodrigues and Antonio 2011). The above-ground biomass was converted into t C ha−1 yr−1 using the IPCC equations for N-fixing forage. A residue management scenario of 50 percent of available residues per ha was modeled for each of the main crops in Africa. green manuring.06 tC/ha. Agroforestry options that produce high-value crops and additional sources of farm revenues offer additional mitigation benefits. and water and nutrient management to improve soil carbon sequestration. the input value for the model was 1. there exists a significant trade-off between residues on the field versus residues used for livestock feeding. There is a significant trade-off between residues on the field versus residues used for livestock feeding. apart from Southeast Asian countries. respectively. In addition. such crops yield around 4 t dry matter ha−1 yr−1. In the dry season. a second crop of rice (where irrigated) or another less water–demanding crop (legumes and coarse grains) is grown. improved fallows in maize systems with several nitrogen-fixing tree species (both coppiced and noncoppiced) resulted in above-ground carbon inputs of 2. A residue management scenario of 50 percent of available residues per ha was modeled for each of the main crops in Asia.

Residue management in rice systems was modeled. and pulses cultivated as winter crops and usually in rotations.2: Agricultural Systems and Mitigation Scenario in Central America MAPPING UNIT/ STRATUM SORGHUM BEANS MAIZE RICE 2 4 6 9 10 12 Mitigation options Source: This study. Green manure using winter cover crops during the fallow period was also modeled. and sorghum. Those in zone 3 are barley. wheat. The main crops are wheat.1: Agricultural Systems and Mitigation Scenario in South America MAPPING UNIT/ STRATUM WHEAT SOYBEAN MAIZE SOYBEAN MAIZE BEANS MAIZE Cover crop Cover crop no-tillage Cover crop RICE AGROFORESTRY 2 4 6 8 9 12 Mitigation options Cover crop residue management Source: This study. In zone 7. Notillage was considered a mitigation option in 50 percent of the cropped area.2). soybean. pulses. North America The dominant crops in mapping unit 1 are barley. Central America Oceania The most dominant agricultural systems in Central America are sorghum. No-tillage was identified as another mitigation option. The use of a cover crop during the fallow period was identified as a promising mitigation opportunity. soybean. rice. No-tillage in soybean/ maize systems was modeled and applied to the area where soybeans and maize are grown. cover crops and residue management of rice-based systems were identified as mitigation options. Compared to South America. In recent years. The agricultural systems found in the mapping units/stratum are displayed in Table B. and maize predominate. and agroforestry (table B. wheat. and pulses. Common land management practices in South America include rotational wheat/soybean and fallow systems. but there are still opportunities to increase its use. Cover crop was modeled and applied to the total area of crops for which green manuring is practiced. maize. no-tillage has been adopted by many producers. Crops are mostly cultivated during the summer with bare fallow during the winter. wheat. EC O N O M I C A N D S E CT OR WORK Cover crop Cover crop Residue management AGROFORESTRY . No-tillage is used in TABLE B. barley. maize. beans/maize.69 AP P E N D I X B — G E NE RAL SCE NARIO ASSUMP T IONS A ND A PPLICATION FOR WORLD REGIONS TABLE B. and tillage.1. maize and soybean systems with residue management. South America Several agricultural systems exist in South America. soybean.

Crop yields were grouped into three bins representing the 25th percentile.085 3 0.70 AP P E NDIX B — GENERA L SC ENA RIO A SS UMPTIONS A ND A PPLIC ATION FOR WORLD R EGIONS fied above. 50 percent.3: Manure C Inputs for the Agroecological Zones (AEZs) in Africa Based on FAOSTAT MAPPING UNIT/AEZ DIRECT MANURE t C/hA/APPL.032 0. and 75 percent) left in the field.4 DETAILED MODELING FOR AFRICA Residue and Integrated Nutrient Management This scenario implies additional residue inputs due to crop management improvement. Tillage is frequently used. 1 0. Russia The main crops are wheat and barley cultivated as summer crops with bare fallow during the rest of the year. and the 75th percentile of the yields of a specific crop in one stratum to assess the opportunity of adapting the residue management to local situations.061 11 0. and poultry for each country of each region.017 0. Cover crops and no-tillage techniques are rarely used (around 1 percent). 7. the raw manure and composted manure model inputs in t C/ha were estimated by applying IPCC factors to the average amount of farm animals per ha (IPCC 2006). Europe The main crops are wheat and barley in winter and maize in summer.136 12 0.035 0. the average value of inputs for the main crops was used. The scenarios modeled include use of no-tillage. Winter cover crops during the fallow period for green manure were also modeled.075 2 0. no-tillage was assumed to be suitable on 35 percent of the cropped area. Each crop was modeled separately. and 8. but if there was more than one cropping season. each season was modeled separately (e. different fractions of residues applied in the field were modeled (25 percent. COMPOSTED MANURE t C/hA/APPL. goats. manure management can be classified into direct manure application and application of composted manure. sheep. For each zone. Similar to the procedure for residue calculation.030 0. and 75 percent). For each mapping unit.057 10 0.078 4 0.046 0. The calculation of residues inputs from the crops was based on the crop yield data identi- Manure Management Generally. the 50th percentile.056 0. the average manure/composted manure production was calculated for its use in the RothC model (table B. No-tillage was modeled with the average value for organic inputs for the two main crops used. pigs.070 5 0.110 8 0.096 0.046 9 0. The average fresh yield (for instance maize) was converted to amount of residues using IPCC Guidelines. CARBON SEQUESTRATION IN AGRICULTURAL SOILS .031 0.019 0.042 7 0. 50 percent.025 0. The C input per ha was calculated based on FAOSTAT numbers of cattle. Direct manure and composted manure application were modeled in combination with different fractions of crop residues (25 percent. Residues are sometimes burnt just before sowing. Residue is commonly left on the field or incorporated (around 75 percent of the cropped area). maize 1s and maize 2s).073 6 0.023 0. B. approximately 50 percent of the cropped area.g..029 0. Cover crops during the fallow period for green manure were also modeled. TABLE B.232 Source: This study.3). To account for possible trade-offs between retention of residues in the field and residues needed as livestock feed. For mapping units 2. the average value for summer and winter cover crops was used. For each climate zone.

Only the mean values of residues were used for the modeling. and Land Rehabilitation Five different agroforestry mitigation scenarios were considered in this study. The input values were calculated 71 . Only mean values of residues EC O N O M I C A N D S E CT OR WORK were used for the modeling. intensive or higher with large scale irrigation 5 Forestry-pastoralism moderate or higher with scattered plantations 17 Agriculture-large scale irrigation (>25% pixel size) 6 Forestry-scattered plantations 18 Agriculture-protected areas 7 Herbaceous-no use/not managed (Natural) 19 Urban areas 8 Herbaceous-protected areas 20 Wetlands-no use/not managed (Natural) 9 Herbaceous-extensive pastoralism 21 Wetlands-protected areas Source: FAO and World Bank.1: FAO Land-Use Map 10 Herbaceous-mod. ƒ Cowpea + maize and cowpea + sorghum: This scenario assumes that cowpeas are predominantly intercropped with maize and sorghum. and groundnuts. Green Manure/Cover Crops (GMCCS) Based on a study by Barahona (2004). the largest share of GMCCs worldwide is from Africa (51 percent) with maize cropping systems being the most dominant (66 percent). (2006) and Anthofer (2005).: An input value of 3. Improved Fallow. The activity data are the crop areas of maize and sorghum. The input values are shown in table B. intensive pastoralism FAO Land use system 11 Herbaceous-intensive pastoralism Undefined 13 Rainfed agriculture (subsistence/commercial) 1 Forestry-no use/not managed (Natural) 14 Agro-pastoralism mod. intensive 2 Forestry-protected areas 15 Agro-pastoralism intensive 4 Forestry-pastoralism moderate or higher 16 Agro-pastoralism mod. The input values are the strata-specific combinations of crop residues of cowpeas in addition to the residues of maize and sorghum. respectively. The General Agroforestry Mitigation Scenario This scenario can be seen as representative for all agroforestry systems on cropland.. The activity data for this scenario are potentially the area of all crops.AP P E N D I X B — G E NE RAL SCE NARIO ASSUMP T IONS A ND A PPLICATION FOR WORLD REGIONS FIGURE B. ƒ Groundnuts + maize and groundnuts + sorghum: This scenario assumes that groundnuts are intercropped with maize and sorghum. The input values are the strataspecific combinations of crop residues of groundnuts in addition to the residues of maize and sorghum. The following GMCCs scenarios are considered for the modeling: ƒ Mucuna sp. Cowpeas. The most frequently used GMCCs are Mucuna sp. Other main crops include cassava and sorghum. respectively. pigeon peas.27 t C/ha/year was used for the modeling in all strata based on Kaizzi et al. Agroforestry. The activity data were the crop areas of maize and sorghum.4.

41 2.27 3.00 COWPEA + SORGHUM (tC/ha/YEAR) 1.33 5. Clay 25.55 0.81 3.27 3.19 0.73 2.55 0.08 2.84 0. Clay 50 AEZ 02.00 1.74 4.00 1.87 2.44 2.87 2.27 3.58 2.74 2.00 1.27 3.64 2.47 3.00 1. N AEZ 11.49 1.34 2.79 1.27 3.27 3. S AEZ 09.00 2.23 3. N AEZ 07.57 1. Clay 25.00 1.08 0.80 2.62 0.27 3.44 1. Clay 75 3.78 1.00 1.27 3. Clay 25. Clay 50.27 3. Note: AEZ = Agroecological Zone.99 2.27 3.81 2.04 2.27 3. S AEZ 08.27 3.36 2.88 3.27 3.95 1. N AEZ 08. Clay 75 AEZ 07.27 3. Clay 25. Clay 25.27 COWPEA + MAIZE (tC/ha/YEAR) 1. N AEZ 08.66 3.27 3. S AEZ 09.81 2.34 1. Clay 50.27 3. Clay 50 AEZ 01.51 3.35 1. Clay 50.11 1. Clay 25 AEZ 03.65 0.00 1.82 3.65 2.68 3.24 1.62 2. Clay 25 AEZ 02.66 1. Clay 25.93 2.62 3.00 1.20 1.06 2.35 2.52 2.85 1.27 3.18 3. Clay 75.84 2.62 0.42 3.27 3.26 2.27 3.58 3.62 2.76 0.90 0. Clay 25 AEZ 05.00 2.27 3.98 1.00 1.27 3.27 3.12 0.71 0.87 1.52 1.72 0. S AEZ 07.73 1.27 3.58 1.62 4. CARBON SEQUESTRATION IN AGRICULTURAL SOILS . N AEZ 07.27 3.72 2.27 3. Clay 50 AEZ 12.27 3.27 3.61 2.50 2.78 4.40 1.69 2.72 1. Clay 75 AEZ 06. S AEZ 12. N AEZ 09.15 2.02 4.89 2. N AEZ 09. S AEZ 08.94 1.00 1.96 3.00 2.73 1. S AEZ 10.45 2. N AEZ 10.06 1. S AEZ 10.27 3.76 1.78 1.12 1.59 2. Clay 75.10 3.77 1. N AEZ 10.55 1.12 3.28 3.71 2.4: C Inputs for Different Green Manure/Cover Crop Systems MAPPING UNIT (AFRICA) MUCUNA (tC/ha/YEAR) AEZ 01.10 4.83 0. Clay 75.61 1.66 0.27 3.40 0.27 3.87 2. Clay 75 AEZ 05.83 2.00 GROUNDNUTS + MAIZE (tC/ha/YEAR) 1. Clay 75.94 2.88 0.00 1. Clay 25 AEZ 04.91 1. Clay 75.71 3.27 3.27 3.27 3.29 2. Clay 25. S AEZ 11.14 1.37 2.00 2.51 3. N AEZ 11. N AEZ 11.49 0.89 1.19 0.88 2.00 0.09 3. N AEZ 10.91 0.00 2.27 3. Clay 50. S AEZ 08.51 1. S AEZ 11.27 3.40 1.43 1.71 3.93 1.02 1. S AEZ 09.72 AP P E NDIX B — GENERA L SC ENA RIO A SS UMPTIONS A ND A PPLIC ATION FOR WORLD R EGIONS TABLE B.03 1.70 3. Clay 50.00 2.27 3.58 GROUNDNUTS + SORGHUM (tC/ha/YEAR) 2.97 3. Clay 50 AEZ 03. N AEZ 07.00 0. N AEZ 09.99 1.57 0. Clay 50 AEZ 05. Clay 75.86 1. S AEZ 07.36 2.61 1.50 1.58 1.27 3. Clay 75.27 3. Clay 50 AEZ 04.17 1. Clay 50 AEZ 06. S AEZ 11.78 2. S AEZ 10.59 1. Clay 25. Clay 50.28 3.53 3.00 0. Clay 25.27 2. Clay 50.13 1.27 3.42 2.81 2. Clay 50.25 3.27 3.44 1.27 3.03 4.27 3.63 1.87 0.45 2. Clay 75 AEZ 04. Clay 25 AEZ 01.00 2.27 3.62 1.40 1.46 1. Clay 75 AEZ 02.79 3.27 3.94 2.73 2.92 3.50 0.00 1. Clay 50.15 2. Clay 75.27 3.00 1.27 3.67 2.19 0.91 3.00 1.23 2.27 3.25 3.00 2. Clay 25 AEZ 06. Clay 75.38 Source: This study.27 3.00 0.00 2.56 0. Clay 75.70 1.27 3. N AEZ 08. Clay 25 AEZ 12.00 1.71 4.85 5.76 1. Clay 50.08 2.71 2. Clay 25.15 0. Clay 75 AEZ 03.91 2.27 3.57 1.

Note: AEZ = Agroecological Zone. Clay 25 AEZ 06. S AEZ 09. N AEZ 11.19 8. Clay 50.17 1. N AEZ 08.04 2.843 3. Clay 75.19 8.843 3.19 8.19 8.19 8.83 3.19 8.05 4.843 3.19 8.96 4.843 3. Clay 75.53 4.58 1.95 3. Clay 50.58 5.94 2.46 3.47 3.77 4. Clay 75 AEZ 04. Clay 25.35 5. S AEZ 10.81 3.17 5.91 3. Clay 50 AEZ 02.17 5. S AEZ 08. Clay 75. N AEZ 09.843 3.03 2.17 5. S AEZ 10. N AEZ 09. Clay 25.19 8.17 5. N AEZ 07.51 4.45 4.15 3.58 5. S AEZ 09.83 3.843 3.25 5.05 3.843 3. S AEZ 08.843 3.19 8.17 1.843 3. Clay 50.65 4.55 4.08 3.96 4.843 3. Clay 25.19 8.17 5. S AEZ 07.19 8.843 3.17 5.843 3. N AEZ 10.33 4.19 8. Clay 50.843 3.41 4.17 5. S AEZ 12. N AEZ 11.62 COPPICED IMPROVED FALLOW + MAIZE (tC/ha/YEAR) 4. Clay 75 AEZ 03. Clay 50 AEZ 12.17 5.843 3.843 3. S AEZ 09.19 8.843 3.17 5.843 3.72 4.843 3.30 5.43 4.843 3.843 3.97 5.36 4.19 8.94 3.843 3.19 8. EC O N O M I C A N D S E CT OR WORK COFFEE AND COCOA SHADE TREE SYSTEMS (tC/ha/YEAR) 8.17 5. S AEZ 07.17 5.45 4.53 4. Clay 25.19 8. Clay 75.843 3.843 3.17 5.843 3.19 8.19 8.17 5.83 5.89 2.843 3.97 2. Clay 25. Clay 25.98 4.19 LEGUME IMPROVED FALLOW + MAIZE (tC/ha/YEAR) 2.19 8.19 8. N AEZ 11. Clay 75.33 4.14 3.843 3.19 8. Clay 75 AEZ 06.96 4.58 1. Clay 50.17 5. S AEZ 08.44 5.58 1.58 5.19 8.96 3.55 4. Clay 50 AEZ 05.843 3.19 8.03 3.843 3. Clay 50.19 8.843 3.5: C Inputs for Different Agroforestry Systems MAPPING UNIT (AFRICA) AGROFORESTRY GENERAL (tC/ha/YEAR) AEZ 01.33 3. Clay 25 AEZ 04.19 8. Clay 75.35 4.73 AP P E N D I X B — G E NE RAL SCE NARIO ASSUMP T IONS A ND A PPLICATION FOR WORLD REGIONS TABLE B.17 5.843 3.06 3.09 2.58 1.90 4. Clay 75 AEZ 07.31 4.17 5.19 8. Clay 50.36 4.32 4.19 8.843 3.35 3.86 2.843 .54 4.19 8.44 3.19 8. Clay 25. Clay 50 AEZ 01. S AEZ 10.19 8.95 2.17 1.55 6.46 4. N AEZ 10.843 3.17 5.93 2.58 5. Clay 25.42 4.843 3.44 4.82 2.843 3.48 2.85 4.843 3.843 3.58 1.17 5.17 5.17 5. Clay 25 AEZ 12.46 2. Clay 25 AEZ 02.17 Source: This study.95 3.17 5.843 3. Clay 25 AEZ 05.17 5.40 3.17 5.19 8. Clay 75.17 5.72 3. Clay 50.843 3.86 3.19 8.843 3.05 2.843 3.47 4.19 8. Clay 50 AEZ 04.843 3.19 8. S AEZ 11.94 2. Clay 75.19 8. Clay 50 AEZ 06.19 8.19 8.27 3. Clay 75 AEZ 02.08 3.17 1.58 5.41 5.46 3.56 4.12 LAND REHABILITATION (tC/ha/YEAR) 3. N AEZ 07.17 5.58 1.17 5.22 5.19 8.843 3.843 3.42 5. Clay 50.843 3.17 5.843 3.19 8.56 4.91 3.17 5.843 3.75 3.843 3.64 4. N AEZ 09.19 8.19 8. Clay 25 AEZ 03.58 1.19 8.19 8.58 5.85 3.17 5. Clay 25.85 3.843 3. Clay 50 AEZ 03.19 8.39 4.19 8.58 5. N AEZ 10.22 3.843 3. Clay 75 AEZ 05.01 3. N AEZ 07. Clay 50.19 8. S AEZ 11.58 1.19 8.80 4.58 5. N AEZ 08.843 3.17 5.92 3.59 4.17 1. Clay 25. Clay 75. Clay 25 AEZ 01.44 4.19 8.94 4.92 4.17 5. N AEZ 08.19 8. Clay 75 1. S AEZ 11.19 8.06 2.45 4. Clay 75.

1997. Fernandez. The input values represent the mean annual input values over the whole system (fallow and cropping period). and Dossa et al. A. Szott. in which leguminous trees and coppiced trees and shrubs are grown in association with crops. In addition. Agroforestry for soil management. and Sanchez 1991. Oelbermann. and Senna siamea. 2005b. Perennial Crop—Tree Systems This scenario considered two cash crops: coffee and cocoa. Due to the nonavailability of reliable spatial data of degraded lands in Africa.. and irrigated agriculture) (see Figure B.1). Callliandra callothyrsus. rain-fed agriculture. agro-pastoralism. 2006). and Sesbania sesban. Following a study by Kaonga and Coleman (2008). The tree species considered are Tephrosia vogelli. Improved Fallows + Maize Improved fallows.1). REFERENCE Young. The input value is based on organic inputs from tree-dominated fallow systems (Szott et al.. These two mitigation scenarios were modeled for all maize areas.74 AP P E NDIX B — GENERA L SC ENA RIO A SS UMPTIONS A ND A PPLIC ATION FOR WORLD R EGIONS as mean values of more than 30 different systems taking into account different climate regions (humid. CAB International.. ƒ Legume improved fallow + maize: This system assumes a 2-year fallow period and a 1-year trees and maize period. Wallingford. Voroney. Palm. van Noordwijk et al. Cajanus cajan. can sequester substantial amounts of C in plants and the soil. It assumes combinations of improved perennial crop management (pruning and mulching) and the introduction of shade trees (see Szott. and Kass 2005a. The input values from the trees are mean values of the different tree species.e. the mitigation potential was applied to the FAO Land Use Systems 7-11 (herbaceous land-use systems in Figure B. two improved fallow scenarios were modeled in association with maize. 2002. 2008). and Sanchez 1991. the mapping unit-specific maize residues were included as organic inputs in this system (mean residues of maize). 1994). and semi-arid) (see Schroeder 1995. The C inputs for the five agroforestry systems are shown in table B. subhumid. Land Rehabilitation Land degradation may be defined as the long-term loss of ecosystem function and productivity caused by disturbances from which land cannot recover unaided. UK CARBON SEQUESTRATION IN AGRICULTURAL SOILS . It is modeled for all areas classified as FAO Land Use System 13-18 (i. ƒ Coppiced improved fallow + maize: This system assumes a 3-year fallow period and a 7-year trees and maize period. and Lemma et al. The tree species considered are Gliricidia sepium.5.

73 6South America 0.47 2.70 2.69 1.56 0.51 1.66 5Europe 2.42 2.06 2.24 7Oceania 3.69 0.56 1. 50TH.11 1.49 8North America 3.58 2.16 4.19 2.21 1.73 1.06 1.79 3.35 1.86 4South America 0.17 5Asia 0.61 2.45 5.97 5. 50TH .18 3.92 1.38 2.36 8Asia 2.69 0.10 1.26 3Asia 1.99 4North America 3.41 2.97 2.1) GR OUPED INTO 25TH . MEDIUM.71 1.75 AP P E N D I X C — G L OBAL CROP YIE L DS ( T HA.61 1.11 10South America 1.59 1North America 2.10 3North America 2.81 1.60 4.98 2.92 2.70 3.15 2.52 2.99 1.02 1Russia 1.36 1.35 1.50 2.68 3South America 1.27 9South America 0.98 6Africa 0.52 1.79 2.15 1.47 4.81 3Africa 0.02 2Oceania 1.26 3Russia 1.26 4.56 7Russia 1.78 3.13 5.10 1.42 4.60 4.92 7Europe 3.83 4Asia 0.26 1.55 2.97 1.89 2.22 4Africa 0.50 3.98 4.90 6North America 1.22 1.93 1.33 1.29 1.03 1.33 1.86 1.44 3Oceania 2.02 2.60 5. AND HIGH BARLEY STRATUM LOW MEDIUM HIGH STRATUM LOW MEDIUM HIGH (Leer) 1.63 1.80 4.35 2Asia 1.04 2.1 YR.69 8South America 1.63 2.37 3Europe 1.78 6Asia 1.88 9Africa 1.75 2Africa 0.08 3.70 0.87 7Africa 0. A ND 75TH PER C ENTILE BINS Appendix C: GLOBAL CROP YIELDS (T HA -1 YR -1) GROUPED INTO 25TH.18 1.35 8Oceania 3.83 11Oceania 2.77 7North America 3.23 9Asia 1.14 2.75 1.70 3.83 EC O N O M I C A N D S E CT OR WORK .58 1.38 2Europe 1.21 2.16 1.61 7Asia 2.41 9Middle America 0.31 2South America 2.72 3.70 11Asia 0.45 2.02 12South America 0.37 1.29 5.83 3.92 2.99 1.52 8Europe 2. AND 75TH PERCENTILE BINS CORRESPONDING TO LOW.63 0.45 1Asia 1.81 2.96 2North America 3.42 2.97 1.73 1.55 2.

89 6Middle America 0.09 1.53 4North America 0.43 0.15 4Asia 0.13 1.96 1.94 1.56 2Asia 0.68 0.92 1. 50TH .78 2.12 9South America 0.47 1.86 1.13 9Middle America 0.76 1.50 0.22 1.39 0.20 1.61 0.67 0.44 0.54 0.02 6North America 0. A ND 75TH PER C ENTILE B INS BEANS STRATUM LOW MEDIUM HIGH STRATUM LOW MEDIUM HIGH 10Africa 0.04 1.81 0.21 5Asia 1.45 2Africa 0.86 1Asia 1.37 1.13 12Asia 0.74 0.49 0.53 6South America 0.48 0.57 0.40 7Europe 3.15 1.19 3.87 3Russia 1.24 1.54 0.86 0.79 7Russia 0.36 0.84 1.55 12Middle America 12South America 0.04 4South America 0.64 3South America 0.98 1.15 3.64 0.65 0.18 1North America 1.17 6Africa 0.51 10Asia 0.45 1.03 1.81 0.83 1.99 1.84 12Africa 0.03 1.47 0.08 8Oceania 1.76 1.87 6Asia 0.54 11Africa 0.62 0.92 2Oceania 1.98 1.46 7Asia 0.47 11Asia 0.47 9North America 0.20 7Oceania 0.75 0.77 0.93 1.82 0.42 0.11 1.35 1.08 CARBON SEQUESTRATION IN AGRICULTURAL SOILS .70 0.56 1.17 0.55 0.71 1.41 1.57 8South America 0.73 0.94 1.72 1.79 2North America 0.68 3North America 1.60 1.54 0.16 1.46 1.60 3Africa 0.50 4Middle America 0.78 0.48 8Europe 2.76 A PP E NDIX C — GL OBAL CROP YIE LD S (T H A -1 YR -1) GR OUPED INTO 25TH .76 7North America 1.25 2South America 0.19 1.71 0.52 0.66 10Middle America 0.71 0.22 8Asia 0.45 0.88 1.67 0.92 1.12 9Asia 0.67 0.02 2.49 0.99 1.86 1.36 2.80 3Oceania 1.65 0.46 1.36 1.67 0.69 0.81 4Africa 0.67 1Russia 1.58 0.24 1.87 1.78 0.39 0.86 10South America 0.82 0.60 9Africa 0.67 3Asia 1.44 1.19 3Europe 0.86 2Europe 0.92 7Africa 0.83 1.05 1.37 0.46 1.73 0.70 0.86 4.93 1.32 0.23 0.87 0.54 11South America 1.39 4.28 1.

28 4.62 0.53 0.81 6.19 2.68 3.79 1Asia 0.05 7North America 6.16 4North America 1.1) GR OUPED INTO 25TH .62 0.26 2North America 1.72 0.35 2.81 1.50 3.55 0.02 2.54 8.55 2.02 9Asia 1.15 1.54 0.99 3Asia 1.89 8Oceania 6.23 3.79 0.23 1.02 7Russia 2.12 6Middle America 1.70 12Middle America 1.97 9Africa 0.25 8.88 0.88 5.48 3.37 2South America 4.50 1.44 7.16 1.75 0.67 0.36 1.54 10Middle America 0.42 7.83 2.18 3Europe 0.66 0.73 5.26 1.68 1.98 4.73 2Asia 0.66 11South America 3.92 1.58 2Asia 0.54 3.26 4.93 1.86 8North America 5.52 2.10 8.34 0.16 6.92 1.44 9North America 0.06 1.12 8Europe 4.78 2.84 1.58 5.77 9Africa 0.78 7Europe 5.86 5.69 5.65 2Africa 1.72 0.21 3North America 6.56 2.23 2.18 MILLET EC O N O M I C A N D S E CT OR WORK .54 12South America 2.89 4.30 4Africa 0.45 2Europe 6.49 3.85 5.96 9.88 2.38 7.11 2Africa 0.43 1.31 12Asia 1.90 1.56 6.56 0.02 3Africa 1.00 1.35 7Asia 3.04 2.08 10South America 1.94 3.49 9Middle America 1.27 3.57 0.46 6.52 3Europe 2.75 4South America 0.82 5.1 YR.39 0.70 2.59 0.64 2.53 8.12 7.20 6Asia 0.62 7Asia 1.26 3North America 1. 50TH .21 1.11 4.05 3South America 2.05 1.65 2.95 6Africa 0.34 9.96 4Africa 0.17 8.54 4Asia 0.89 3Africa 0.41 STRATUM LOW MEDIUM HIGH STRATUM LOW MEDIUM HIGH 11Asia 1.85 6North America 1.78 1.76 1North America 6.43 1.99 11Africa 1.75 5Asia 1.60 2.40 6.62 9Asia 0.87 3.42 2.79 7.30 7.59 3.44 4.01 1.82 4.12 1.70 8Africa 3.94 1.03 1.08 5Asia 3.80 1.35 11Asia 1.22 1.20 5.96 8Asia 0.86 4Middle America 0.83 3Asia 3.61 3.44 7.59 6.08 2.29 5.97 1Asia 4.53 4.04 2Oceania 3.34 0.66 8South America 3.67 1.42 6South America 1.73 3.03 12Africa 0.38 2.66 0.11 2.82 1.73 2North America 3. A ND 75TH PER C ENTILE BINS MAIZE STRATUM LOW MEDIUM HIGH STRATUM LOW MEDIUM HIGH 10Africa 0.85 2.06 4Asia 1.43 6Africa 0.89 1.84 2.41 1.32 3.28 10.15 1.88 2.88 1.95 1.64 2.35 7Africa 1.83 1.96 3.18 1.84 1.22 1.47 9South America 1.77 AP P E N D I X C — G L OBAL CROP YIE L DS ( T HA.96 9.33 4.45 1.88 2.29 6Asia 2.80 8Asia 2.80 5.54 3.71 1.14 10Asia 1.

05 4.09 9Asia 2.82 1.80 12Middle America 2.79 5.33 5.42 4.70 0.59 3Asia 3.70 0.74 4.67 2.15 3Africa 1.89 1.17 7Asia 5.84 2Europe 6.97 5.36 6South America 1.68 2Middle America 0.40 3.58 3.49 5.21 2Asia 2.85 3.95 1.74 6.45 3.70 4.81 2South America 4.26 3.26 4.90 5.12 4.24 2.54 3.94 1.07 2.22 4.93 4.60 2.70 8South America 4.96 7North America 6.16 3.44 11Oceania 2.71 6.61 2.42 4.18 6Asia 0.81 4Asia 1.10 1.70 0.70 6.42 6Middle America 3.04 3Asia 3.66 4.23 7Russia 3.14 4North America 1.17 6South America 3.73 6.14 9North America 1.08 3.08 6.28 4.45 6.05 11Asia 0.69 3.82 6North America 4.57 4.77 1.69 7.38 4Africa 0.12 10Middle America 2.43 4.31 12Asia 2.15 6.18 3.53 2Asia 0.29 9.81 3.24 1.31 7Europe 5.54 8.19 6Asia 3.57 6.73 1.02 1.45 0.46 6Africa 0.32 4.05 3.75 2Africa 4.91 3.34 6.78 8.23 7North America 4.89 6.27 9.71 4.54 3.07 3North America 3.64 3.54 2.45 4.54 5Asia 4.38 0.31 3.74 0.71 0.52 3.44 11Asia 2.23 6.67 9Africa 1.14 3.15 3Oceania 2.63 2Oceania 2.34 12Africa 1.38 8Asia 0.43 2.53 3.44 4.39 4.15 8Europe 6.51 0.69 2.13 2.69 8North America 5.37 11Africa 0.28 5Asia 3.90 4South America 0.37 5.46 6.97 4.01 10South America 2.33 1.21 8Oceania 2.79 9Middle America 2.50 5.33 2North America 7.19 7.09 7Oceania 3.60 3.64 1.78 6North America 5.71 4South America 2.82 2North America 2.57 4Asia 0.04 2.02 3North America 9.78 9Asia 0.59 1.16 2.81 3.18 8Asia 4.24 6.10 3.91 6.39 5.75 2.17 6.20 4.83 4.66 3.59 4.18 6.70 2Africa 0.67 3South America 5.59 10South America 3.16 4North America 4.79 9Africa 0.78 3.30 8North America 4.95 5.70 1Asia 5.70 3Russia 3.13 1.75 2.22 3.92 1Asia 3.13 4.51 8South America 4.56 2.20 3.35 6.65 3. A ND 75TH PER C ENTILE B INS 78 RICE SORGHUM STRATUM LOW MEDIUM HIGH STRATUM LOW MEDIUM HIGH 10Africa 1.98 2Oceania 8. 50TH .93 9.09 3.39 8.94 6.70 0.45 2.23 2.90 3.30 3.84 1.22 9.36 2.56 4Africa 0.68 5.77 9South America 1.02 1.80 12South America 2.14 3.80 1.55 1.79 3.75 4.96 3Europe 3.78 1.48 4.33 4Middle America 0.01 6.66 CARBON SEQUESTRATION IN AGRICULTURAL SOILS .52 6.72 7Asia 3.25 5.83 4.64 2.37 2.26 6.14 3.18 2.27 10Asia 3.55 4.62 0.60 4Middle America 2.A P P E NDIX C — GL OBAL CROP YIE LD S (T H A -1 YR -1) GR OUPED INTO 25TH .72 6Africa 1.38 3.43 2.62 1.99 6.81 1.58 0.19 1.77 7.13 3.26 5.91 3.97 6.48 0.64 6Middle America 0.13 9South America 1.17 2.63 9Middle America 0.29 3.62 2.68 12South America 2.01 2South America 4.54 4.

88 8Asia 1.82 2.35 9Middle America 1.55 EC O N O M I C A N D S E CT OR WORK .02 2South America 2. 50TH .77 0.34 2.96 3Asia 1.25 9North America 1.46 1.83 9Asia 1.31 1.33 2.40 2.96 1.34 2Africa 1.51 0.21 1.50 1.06 1.35 2.76 6South America 2.98 1.95 2.86 3.45 1.79 AP P E N D I X C — G L OBAL CROP YIE L DS ( T HA.50 9Africa 0.69 1.21 2.18 2.23 2.86 1.49 2.24 1North America 1.25 6Asia 0.07 2North America 1.06 3.09 1.84 2.60 2.19 2.06 1.13 1.04 2.47 2.61 0.01 12South America 2.91 11Asia 0.41 2.72 1Asia 1.04 2.75 0.07 1.13 2.89 3North America 2.76 11South America 2.59 5Asia 1.55 7North America 2.61 3.31 1.95 4South America 1.10 1.79 2.50 2Oceania 1.56 2.31 4Asia 0.80 2.63 2.97 4Africa 0.19 10South America 2.34 1.16 1.77 1.77 2.63 3Europe 1.36 2Europe 2.1) GR OUPED INTO 25TH .55 2.37 2.27 4North America 0.45 2.83 1.1 YR. A ND 75TH PER C ENTILE BINS SOYBEANS STRATUM LOW MEDIUM HIGH STRATUM LOW MEDIUM HIGH 10Asia 1.08 1.44 2.26 9South America 2.02 1.52 2.28 1.75 1.17 1.29 2.63 1.39 8Europe 2.40 1.97 1.47 0.06 1.55 12Asia 1.53 1.59 0.00 1.11 2.98 2.95 7Russia 1.74 1.70 0.58 3South America 2.02 1.27 7Europe 2.90 8South America 2.14 1.35 7Asia 1.82 2Asia 0.55 1.46 2.81 2.93 1.48 6Africa 0.02 8North America 1.55 8Oceania 1.35 2.

77 2.58 2.02 1.96 7Oceania 2.31 4.33 5.38 8Oceania 2.54 2South America 2.52 2Oceania 1.56 1.08 2Asia 1.61 2Africa 0.75 3South America 1.29 4Africa 0.30 4.61 3.32 3Europe 1.36 11Asia 1.48 1.31 2Europe 1.27 5.19 2.00 7North America 3.80 A P P E NDIX C — GL OBAL CROP YIE LD S (T H A -1 YR -1) GR OUPED INTO 25TH .71 3.20 2. A ND 75TH PER C ENTILE B INS WHEAT STRATUM LOW MEDIUM HIGH STRATUM LOW MEDIUM HIGH 10Asia 1.60 3.87 1.39 2North America 1.70 1.48 2.01 10South America 1.92 1.77 12South America 1.56 1.70 3.99 9Asia 1.41 2.91 1North America 1.03 2.51 3Africa 0.86 Source: This study.42 7Africa 0.55 1.48 1.07 3.68 1.91 8North America 2.05 1.38 2.72 2.64 1Russia 1.87 2.00 1.33 5Russia 0.69 4Asia 1.84 2.82 2.30 2.13 1.30 3.05 5.57 3Russia 1.23 2.01 3.72 2.48 1.99 4North America 4.46 5.11 6.53 11Africa 1.81 1.96 1.92 2.70 2.67 1.92 4South America 0.05 3.51 4.19 1.08 3.67 4.46 7Asia 2.84 1.66 4.76 8Europe 2.66 3.83 1.01 5.71 1.83 2.66 9Middle America 1.98 2.42 6Asia 1.25 3Asia 1.61 11South America 2.85 2.31 6. CARBON SEQUESTRATION IN AGRICULTURAL SOILS .33 1. 50TH .28 3.49 5Asia 1.68 2.58 9Africa 1.27 2.30 2.44 6Africa 1.19 7Europe 4.04 6South America 1.24 2.41 1.10 2.10 2.06 1.36 3.70 7.92 4.87 3Oceania 1.18 5Europe 2.36 8South America 1.76 2.55 1Asia 0.85 2.05 1.95 2.29 3.69 2.08 4.52 1.96 3.68 0.64 4.63 9South America 1.23 1.22 2.62 3North America 1.15 7South America 4.08 7Russia 2.11 2.31 11Oceania 2.03 9North America 1.30 1.16 8Africa 6.97 2.95 6North America 2.67 3.74 2.21 1.85 1.55 3.80 4.74 1.20 2.63 3.09 1.26 1.48 8Asia 1.58 2.

EC O N O M I C A N D S E CT OR WORK Pmin = X p − 1. For each mapping unit. monthly precipitation. t − PRSmin. The uncertainty (UNC) in the output model was finally calculated as UNCt = | PRSmax. SEp is the standard error in the mean of parameter p in year t. t. The input parameters for which the uncertainty was estimated were minimum and maximum monthly temperatures. t | . The minimum Pmin and maximum Pmax values of the confidence interval for the mean of the parameters X p were estimated as The analysis calculates the soil model response using the model input parameters with the upper and lower confidence levels. Pmax is the maximum value of the parameter at the 95 percent confidence interval. the mean values and the standard deviation for the three parameters were calculated. np represents the total number of data points of a parameter used in this analysis for each mapping. two separate models were done with the minimum and maximum values as model inputs.81 AP P E N D I X D — U NCE RTAINT Y ANALYSIS Appendix D: UNCERTAINTY ANALYSIS Uncertainty in the RothC soil carbon modeling was estimated following the adoption of Sustainable Agricultural Land Management methodology. For each of these 20 data points.96 is the value of the cumulative normal distribution at the 95-percent confidence interval. 2. Twenty repetitions were selected randomly among the different scenarios and years for which SOC change values were modeled (table D. and np is the number of samples used to calculate the mean and standard deviation of parameter p. ∂p is the standard deviation of the parameter p in year t. respectively. The range of model responses demonstrates the sensitivity of the soil modeling. and 1. A precision of 15 percent at the 95-percent confidence level was chosen as the criterion for reliability.96 × SE p 1.1). In this case. and clay content in percent of the soil. where SEp is the standard error in the mean of parameter p in year t. the standard error in the mean was estimated using SE p = ∂p np . t and PRSmax. 2 × PRSt . Thereafter. Carbon sequestration rates using the minimum and maximum values of the input parameters are given by PRSmin.96 × SE p where Pmin is the minimum value of the parameter at the 95 percent confidence interval. Uncertainty analysis took place in two steps: Pmax = X p + 1.

3% AEZ09-50 S 75% Maize 25% Residue 2032 2. CARBON SEQUESTRATION IN AGRICULTURAL SOILS .7% AEZ11-50 N 50% Wheat 15% Baseline 2035 7.1 percent.8% AEZ12-50 75% Maize 75% Residue + compost 2029 25.9% AEZ10-50 S 75% Maize 25% Residue + manure 2027 3. The uncertainty ranges from below 1 percent to 26 percent with an average value of 5.A PPEND IX D — UNCERTA INTY A NA LY S IS 82 TABLE D.2% AEZ10-50 S 25% Maize 75% Residue 2020 3.9% AEZ06-50 50% Sorghum 2s 15% Baseline 2021 1. Note: UNC = Uncertainty .1% Source: This study.5% AEZ11-50 N 50% Wheat 25% Residue 2017 10.5% AEZ06-50 50% Sorghum 1s 75% Residue 2025 0.8% AEZ06-50 75% Sorghum 2s 75% Residue + compost 2030 0.7% AEZ09-50 N 75% Maize 25% Residue 2016 9.6% Average: 5.9% AEZ07-50 S Mucuna Cover crop 2024 0.9% AEZ08-50 N 75% Maize 15% Baseline 2026 6.1: Uncertainty Analyses Using Random Samples from the Mitigation Scenarios SCENARIO MAPPING UNIT YIELD BIN CROP RESIDUE FRACTION MITIGATION SCENARIO YEAR UNC t AEZ01-50 50% Maize 1s 50% Residue 2012 2.4% AEZ04-50 50% Maize 1s 75% Residue + compost 2019 2.9% AEZ10-50 S 50% Maize 75% Residue 2027 6. AEZ = Agroecological Zone.9% AEZ11-50 N 25% Barley 75% Residue 2034 10.3% AEZ02-50 25% Millet 50% Residue 2014 2.5% AEZ06-50 50% Maize 2s 50% Residue 2025 1.0% AEZ04-50 75% Rice 2s 25% Residue + compost 2029 1.1% AEZ03-50 50% Sorghum 1s 50% Residue 2019 1.

2) under each of the four IPCC scenarios was allocated to land-use and agroforestry-related land management practices in equal proportion. About 3. rotation intensification. (2008). Sustainable biochar application was assumed for 15 percent of current tree crop area for B1 and B2 scenarios. Two-thirds of this was applied to improved irrigation and rainwater harvesting in equal proportions. rotation diversification. This was assumed to increase by 5 percent under scenarios A2 and B2 and by 6 percent under the remaining two scenarios. The difference between current (table E.2). and crop residue application. manure. No-tillage was assumed to cover 2 percent of cropland area in the B1 and A1B scenarios.1) and the projected cropland area (table E. Organic soil restoration was applied to the estimated degraded peat land area of 13 million ha for each scenario. Grassland The respective abatement rates for fertilizer. about 7 percent increase in potential irrigable area for 1990.6 million ha were estimated as having erosion hazard in Africa.2) under each of the four IPCC scenarios was allocated to land-use and agroforestry-related land management practices in equal proportion. The remaining cropland area under each scenario was distributed evenly among inorganic fertilizer. (2008).1 ASSUMPTIONS FOR DERIVING THE APPLICABLE MITIGATION AREA FOR THE LAND MANAGEMENT PRACTICES AFRICA Asia Cropland Cropland The difference between current (table E.8 Asia 497.1) and projected cropland area (table E. Terracing and sloping barriers were applied to 75 percent of this land area in equal proportion. Biochar was applied to only 15 percent of the applicable area for each agroforestry-related practice for each scenario.AP P E N D I X E — A S S UMP T IONS F OR DE RIVING T HE A PPLICA B LE MITIGATION A REA FOR TH E LA ND MA NA GEMENT Appendix E: E. rotation intensification. while it was assumed to increase by the same proportion for total cropland area under the remaining two scenarios. cover crops. pasture establishment on degraded land.5 million ha under each scenario. 83 . TABLE E. but only 1 percent in the remaining two scenarios. The remaining cropland area under each scenario was distributed evenly among inorganic fertilizer. No-tillage is currently practiced on 3 percent of land in Asia.1: Estimated Cropland Area in the 2000s MILLION ha Africa 165. The abatement rate for organic soil restoration was taken from Smith et al.4 Latin America 110. but by just 15 percent under the two other scenarios that are more environmentally focused. manure. and it was assumed to increase to 7 percent of current land area by 2030 for all scenarios. Tree-crop farming was projected to increase by the same proportion the entire cropland area for the continent increased for A1B and A2 (the more economic focus scenarios). improved pastures. Land devoted to intensive vegetables was assumed to increase by 15 percent under the B1 and B2 scenarios. and 15 percent of projected tree crop area for the remaining two scenarios. and rainwater harvesting were each applied to one-sixth of projected grassland area for each of the four IPCC scenarios for the continent by 2030 (table E.3 Source: Based on Monfreda et al. cover crops. and crop residue application. EC O N O M I C A N D S E CT OR WORK Current land area under biofertilizer is 29 million ha. manure. Rainwater harvesting was assumed applicable to 19. The estimated irrigable area in Asia is 270 million ha.

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