B. A. Stewart

SOIL CARBON SEQUESTRATION TO MITIGATE CLIMATE CHANGE AND ADVANCE FOOD SECURITY

World soils have been a source of atmospheric carbon dioxide since the dawn of settled agriculture, which began about 10 millennia ago. Most agricultural soils have lost 30% to 75% of their antecedent soil organic carbon (SOC) pool or 30 to 40 t C ha−1. The magnitude of loss is often more in soils prone to accelerated erosion and other degradative processes. On a global scale, CO2-C emissions since 1850 are estimated at 270 ± 30 giga ton (billion ton or Gt) from fossil fuel combustion compared with 78 ± 12 Gt from soils. Consequently, the SOC pool in agricultural soils is much lower than their potential capacity. Furthermore, depletion of the SOC pool also leads to degradation in soil quality and declining agronomic/biomass productivity. Therefore, conversion to restorative land uses (e.g., afforestation, improved pastures) and adoption of recommended management practices (RMP) can enhance SOC and improve soil quality. Important RMP for enhancing SOC include conservation tillage, mulch farming, cover crops, integrated nutrient management including use of manure and compost, and agroforestry. Restoration of degraded/desertified soils and ecosystems is an important strategy. The rate of SOC sequestration, ranging from 100 to 1000 kg ha−1 year−1, depends on climate, soil type, and site-specific management. Total potential of SOC sequestration in the United States of 144 to 432 Mt year−1 (288 Mt year−1) comprises 45 to 98 Mt in cropland, 13 to 70 Mt in grazing land, and 25 to 102 Mt in forestland. The global potential of SOC sequestration is estimated at 0.6 to 1.2 Gt C year−1, comprising 0.4 to 0.8 Gt C year−1 through adoption of RMP on cropland (1350 Mha), and 0.01 to 0.03 Gt C year−1 on irrigated soils (275 Mha), and 0.01 to 0.3 Gt C year−1 through improvements of rangelands and grasslands (3700 Mha). In addition, there is a large potential of C sequestration in biomass in forest plantations, short rotation woody perennials, and so on. The attendant improvement in soil quality with increase in SOC pool size has a strong positive impact on agronomic productivity and world food security. An increase in the SOC pool within the root zone by 1 t C ha−1 year−1 can enhance food production in developing countries by 30 to 50 Mt year−1 including 24 to 40 Mt year−1 of cereal and legumes, and 6 to 10 Mt year−1 of roots and tubers. Despite the enormous challenge of SOC sequestration, especially in regions of warm and arid climates and predominantly resource-poor farmers, it is a truly a win-win strategy. While improving ecosystem services and ensuring sustainable use of soil resources, SOC sequestration also mitigates global warming by offsetting fossil fuel emissions and improving water quality by reducing nonpoint source pollution.

Climate change and global food security

PREFACE CONTRIBUTORS GLOBAL FOOD SECURITY Reducing World Hunger in Tropical Africa while Coping with Climate Change, P.A. Sanchez World Food Security: Perspectives, Past, Present, and Future, D.J. Greenland Changing Times and Directions, R.D. Havener, C.R. Dowswell, and N.E. Borlaug Greenhouse Gases and Food Security in Low-Income Countries, R. Darwin, S. Rosen, and S. Shapouri Climate Change, Soil Carbon Dynamics, and Global Food Security, R. Lal CLIMATE CHANGE AND NET PRIMARY PRODUCTIVITY Climate Change Effects on the Water Supply in Some Major River Basins, R.S. Muttiah and R.A. Wurbs Climate Change and Terrestrial Ecosystem Productivity, W.M. Post and A.W. King The Changing Role of Forests in the Global Carbon Cycle: Responding to Elevated Carbon Dioxide in the Atmosphere, E.H. Delucia, D. J. Moore, J.G. Hamilton, R.B. Thomas, C.J. Singer, and R.J. Norby Impact of Climate Change on Soil Organic Matter Status in Cattle Pasture in Western Brazilian Amazon, C. C. Cerri, M. Bernoix, C.E.P. Cerri, and K. Paustian CLIMATE CHANGE AND AGRONOMIC PRODUCTION Climate Change, Agriculture, and Sustainability, C. Rosenzweig and D. Hillel Assessing the Consequences of Climate Change for Food Security: A View from the IPCCW, Easterling Climate Change and Tropical Agriculture: Implications for Social Vulnerability and Food Security, H. Eakin Effects of Global Climate Change on Agricultural Pests: Possible Impacts and Dynamics at Population, Species-Interaction And Community Levels, A. Joern, J. D. Logan, and W. Wolesensky Food Security and Production in Dryland Regions, B.A. Stewart Climate Change and Crop Production: Challenges to Modeling Future Scenarios, E.S. Takle and Z. Pan SOIL CARBON DYNAMICS AND FARMING/CROPPING SYSTEMS Soil Carbon Sequestration: Understanding and Predicting Responses to Soil Climate and Management, J. Jones, V. Walen, M. Doubmia, and A.J. Gijsman Reducing Greenhouse Warming Potential by Carbon Sequestration in Soils: Opportunities, Limits and Tradeoffs, J. Duxbury Management Practices and Carbon Losses via Sediment and Subsurface Flow, L.B. Owens and M.J. Shipitalo Measuring and Monitoring Soil Carbon Sequestration at the Project Level, R.C. Izaurralde Dynamics of Carbon Sequestration in Various Agroclimatic Zones of Uganda, M. M. Tenywa, M. Mwanjalolo, M.K. Magunda, R. Lal, and G. Taulya Soil Carbon Sequestration in Dryland Farming Systems, P. Koohafhan, A. Rey and J. Antoine. More Food, Less Poverty? The Potential Role of Carbon Sequestration in Smallholder Farming Systems in Senegal, P. Tschakert Hillside Agriculture and Food Security in Mexico: Advances in the Sustainable Hillside Management Project, J.I. Cortes, A. Turrent, P. Diaz, L. Jimenez, E. Hernandez, and R. Mendoza Soil Organic Carbon, Quality Index and Soil Fertility in Hillside Agriculture, J.D. Etchevers, M.A. Vergara, M.M. Acosta, C.M. Monreal, and L. Jimenez Terrestrial Carbon Sequestration in Zambia, R.B. Dadson, J. Joshi, F.M. Hashem, A.L. Allen, C. Bolek, S.W. Muliokela, and A. Chalebesa POLICY AND ECONOMIC ISSUES Policy and Economic Issues Dealing with Global Warming, G. E. Schuh Confronting the Twin Problems of Global Warming and Food Insecurity, L. Tweeten Policies and Incentive Mechanisms for the Permanent Adoption of Agricultural Carbon Sequestration Practices in Industrialized and Developing Countries, J.M. Antle and L.M. Young The Impact of Climate Change in a Developing Country: A Case Study from Mali, T. Butt and B. McCarl TOWARDS RESEARCH AND DEVELOPMENT PRIORITIES Researchable Issues and Development Priorities for Countering Climate Change, R. Lal, B.A. Stewart, D.O. Hansen and N. Uphoff INDEX

Need for Land Restoration

Sustainable management of natural resources involves the concept of “using, improving, and restoring” the productive capacity and life-support processes of soil—the most basic of all natural resources. The objective is not only to minimize soil degradation but to reverse the trend through restorative measures of soil and crop management. The soil quality and its productive capacity must be enhanced beyond preservation (status quo) through soil-building measures, e.g., preventing soil erosion and enhancing development of the rooting depth, replenishing nutrients harvested in crops and animals through judicious use of mineral fertilizer and organic amendments and effective nutrient recycling practices, encouraging biological activity of soil fauna, and improving soil organic matter content. The land use or farming system to be adopted must be “soil-restorative” rather than “soil-depletive,” “fertility-mining,” or “soil-degrading.” In addition, soil should not be misused as a dumping ground for toxic wastes. Although soil has a built-in resilience, there is a limit to the abuse that it can withstand.

Climate Change and Terrestrial Carbon Sequestration in Central Asia

This book brings together current knowledge of terrestrial C sequestration in Central Asia. The themes treated include: biophysical environments, water resources, sustainable agriculture, soil degradation, the effects of irrigation schemes on secondary salinization, soil management and its relationship to carbon dynamics; the relationship between forest management and carbon dynamics, economic analyses of land use practices, important methodological issues arising from the use of GIS, remote sensing, carbon budgeting and scaling, and a review of the knowledge gaps in carbon and climate change. The book is a reference source for soil, water, vegetation, climate, land use and management in the region. The book will be of interest to a wide variety of environmental scientists, economists and those interested in policy issues for the sustainable management of natural resources.

Soil Quality and Biofuel Production

Soil Processes and Residue Harvest Management Jane M.F. Johnson, Sharon K. Papiernik, Maysoon M. Mikha,Kurt A. Spokas, Mark D. Tomer, and Sharon L. Weyers Soil Quality Impacts of Residue Removal for Biofuel Feedstock Richard M. Cruse, M.J. Cruse, and D.C. Reicosky Ecological Consequences of Biofuels W.E.H. Blum, M.H. Gerzabek, K. Hacklander, R. Horn, F. Reimoser, W. Winiwarter, S. Zechmeister-Boltenstern, and F. Zehetner Land Use in Production of Raw Materials for Biofuels Leidivan Almeida Frazao, Karina Cenciani, Marilia Barbosa Chiavegato, Carlos Clemente Cerri, Brigitte Josefine Feigl, and Carlos Eduardo P. Cerri Corn and Cellulosic Ethanol Problems and Soil Erosion D. Pimentel Ethanol Production from Sugarcane and Soil Quality M.V. Galdos, Carlos Clemente Cerri, M. Bernoux, and Carlos Eduardo P. Cerri Economic Balance: Competition between Food Production and Biofuels Expansion Jozsef Popp Opportunities and Challenges of Biofuel Production Rattan Lal

Need for Action: Research and Development Priorities

Understanding principles and processes of soil’s life support systems is an important pre-requisite to our ability to produce food, feed, and fiber for the world population, and to preserve a healthy status of global environment. Because the problem of soil degradation is very complex, it is important that we approach the issue in a systematic and logical manner. Some important issues to be addressed as researchable priorities are discussed in the following sections.

Urban Soil Mapping through the United States National Cooperative Soil Survey

Soils accumulate about 1500-2000 Pg (1015 g) C, providing the largest stock in terrestrial ecosystems (Swift, 2001; Janzen, 2004). Historically, soil organic carbon (SOC) is a widely accepted indicator of soil quality. For example, SOC depletion is used as a basic indicator of soil degradation (Nortcliff, 2002; Bastida et al., 2008). The shift in recent decades from traditional agricultural attitudes of soil as a substrate for food production to its role in essential ecological processes and functions highlighted the importance of soil carbon stocks and fluxes (Bolin et al., 1979; Kovda and Rozanov, 1988). Carbon 62sequestration, for example, is an important process to mitigate climate change (IPCC, 2001; Lal, 2004; Janzen, 2004), whereas soil respiration is the largest biogeochemical carbon efflux into the atmosphere, contributing to climate change (Raich et al., 2002; Schulze, 2006). Soil microbial carbon indicates the soil’s performance as a habitat for microorganisms. Soil microbial communities contribute to biodiversity and gene reservoirs (Andrews et al., 2004; Blum, 2005; Dobrovolsky and Nikitin, 2012). The relation between soil microbial carbon and microbial respiration defines the microbial metabolic coefficient, which is widely accepted as a relevant indicator of the state of microbial soil communities and ecosystem disturbance (Anderson and Domsch, 1985; Dilly et al., 2003; Bastida et al., 2006). Many studies classifying and assessing soil functions acknowledge the role of SOC (e.g., BBodSchG, 1998; Karlen et al., 2003; Andrews et al., 2004; Blum, 2005; Dobrovolsky and Nikitin, 2012; Table 3.1). Although reviewed approaches to classify soil functions differ in terms of definitions and labels of each function, their total number, and the classification’s major purpose, they all consider SOC as an important parameter: up to two thirds of the soil functions are directly or indirectly related to SOC stocks. The recently emerged concept of ecosystem services (ESs; MA, 2003) expands the analysis of environmental properties, processes, and functions with human economic benefits (de Groot, 1992; Costanza et al., 1997). Although soil services are considered part of ESs (Breure et al., 2012), SOC directly or indirectly affects many specific ESs, including soil fertility maintenance, food production, and climate regulation (MA, 2003; TEEB, 2010). Currently, most of the carbon assessments focus on natural (forest/meadows) and agricultural ecosystems (e.g., Islam and Weil, 2000; Valentini et al., 2000; Hamilton et al., 2002; Cruvinel et al., 2011; Fromin et al., 2012). Much less, however, is known about the effect of urbanization on soil carbon stocks and fluxes.

The nitrogen dilemma: Food or the environment

Nitrogen (N) is the most important essential element for crop production because it is required in large amounts and is nearly always the first nutrient that becomes limiting after an ecosystem is converted to cropland. Cereal grains provide about 50% of the worlds calories, and their production has become largely dependent on the use of synthetic N fertilizer. However, fertilizer N not used by plants can degrade the environment and negatively impact both people and ecosystems. In addition, efficient use of N fertilizer generally requires phosphorus (P) fertilizer which is made from rock phosphate derived from mines. Therefore, huge amounts of N and P from outside sources are being added to the environment each successive year leading to additional environmental concerns. RISE IN NITROGEN FERTILIZER USE By the early 1800s, it was becoming increasingly clear that there was a great need for N fertilizers. Europeans began importing guano (solidified bird excrement) and sodium nitrate (NaNO3) from South America (Smil 2001), but it became apparent that supplies of these N sources would be insufficient. Coal contains between 1% and 1.6% N, derived from the decomposition of proteins that were present in the biomass that was eventually transformed by pressure and heat…