Forum
Soil Carbon Sequestration in Grazing Lands: Societal Benefits and Policy Implications

https://doi.org/10.2111/08-225.1Get rights and content

Abstract

This forum manuscript examines the importance of grazing lands for sequestering soil organic carbon (SOC), providing societal benefits, and potential influences on them of emerging policies and legislation. Global estimates are that grazing lands occupy ~3.6 billion ha and account for about one-fourth of potential carbon (C) sequestration in world soils. They remove the equivalent of ~20% of the carbon dioxide (CO2) released annually into the earth’s atmosphere from global deforestation and land-use changes. Atmospheric CO2 enters grazing lands soils through photosynthetic assimilation by green plants, subsequent cycling, and sequestration of some of that C as SOC to in turn contribute to the ability of grazing lands to provide societal (environmental and economic) benefits in every country where they exist. Environmental benefits provided include maintenance and well-being of immediate and surrounding soil and water resources, air quality, human and wildlife habitat, and esthetics. Grazing lands contribute to the economic well-being of those living on the land, to trade, and to exchange of goods and services derived from them at local, regional, or national levels. Rates of SOC sequestration vary with climate, soil, and management; examples and conditions selected from US literature illustrate the SOC sequestration that might be achieved. Public efforts, policy considerations, and research in the United States illustrate possible alternatives that impact grazing lands. Discussion of US policy issues related to SOC sequestration and global climate change reflect the importance attached to these topics and of pending legislative initiatives in the United States. Addressing primarily US policy does not lessen the importance of such issues in other countries, but allows an in-depth analysis of legislation, US Department of Agriculture program efforts, soil C credits in greenhouse gas markets, and research needs.

Resumen

Este manuscrito examina la importancia de las “tierras de pastoreo” en el secuestro de carbono orgánico en el suelo (COS) y en la provisión de beneficios a la sociedad, y las influencias potenciales que las políticas y legislación emergentes puedan tener sobre las características mencionadas. Según estimaciones globales, las tierras de pastoreo ocupan ~3.600 millones ha e incluyen aproximadamente un cuarto del potencial edáfico mundial de secuestro de carbono. Remueven el equivalente a ~20% del dióxido de carbono (CO2) liberado a la atmosfera anualmente por la deforestación y los cambios en el uso de la tierra. El CO2 atmosférico ingresa en las tierras de pastoreo mediante la asimilación fotosintética de plantas verdes, el ciclado subsecuente, y el secuestro de parte de ese C como COS que a la vez hace que las tierras de pastoreo puedan proveer beneficios (tanto ambientales como económicos) a la sociedad de todo país que contenga dichas tierras. Los beneficios ambientales que las mismas proveen incluyen el mantenimiento y bienestar de suelos y agua adyacentes y cercanos, la calidad del aire, el hábitat humano y para la fauna silvestre, y los valores estéticos. Las tierras de pastoreo contribuyen al bienestar económico de quienes viven de la tierra, permitiéndoles el comercio e intercambio de los bienes y servicios derivados de dichas tierras a nivel local, regional, o nacional. Las tasas de secuestro de COS varían con el clima, el suelo, y el manejo; ejemplos y condiciones seleccionadas de la literatura de los EE.UU. ilustran los niveles de secuestro de COS factibles de alcanzar. Esfuerzos públicos, consideraciones de políticas, e investigación en los EE.UU. ilustran las posibles alternativas que impactan las tierras de pastoreo. La discusión de temáticas asociadas con las políticas de los EE.UU. en relación con el secuestro de COS y el cambio climático global reflejan la importancia que se le asigna a estos temas y a la legislación pendiente en los EE.UU. El abordaje de las políticas de los EE.UU., no va en desmedro de la importancia de esta temática en otros países, pero permite un análisis detallado de la legislación, los programas del USDA, de los créditos de C edáfico en mercados climáticos, y de necesidades de investigación.

Section snippets

INTRODUCTION

Grazing lands represent the largest and most diverse land resource in the world. More than half of the world’s land surface is grazed. Nearly 100 of the world’s countries have at least one-half and 130 countries have at least one-third of their agricultural land area in grazing lands. Areawise, there are 27 countries with more than 30 million ha (Mha) and 9 countries having more than 100 Mha of grazing lands (Food and Agricultural Organization of the United Nations [FAO] 2004). In the United

SOIL CARBON SEQUESTRATION IN GRAZINGLANDS

Only recently have scientists begun to document soil C content and to study C dynamics on grazing lands maintained for many decades under different management regimes. Therefore, knowledge of soil organic carbon (SOC) sequestration on grazing lands is limited. Predicting the sequestration potential is complicated by several factors, including wide regional and yearly climate variation; complexity of plant communities; presence and proportions of nitrogen (N)-fixing plants; type, species, and

Sequestration of Atmospheric CO2

Among the environmental benefits recognized with C sequestration is to offset atmospheric CO2 emissions by storing CO2 long term in soil organic matter (SOM), thus helping to improve the soil’s productivity. Practices and policies that encourage maintaining and improving soil C sequestration can consistently be associated with improved soil and water quality; reductions in silt loads and sediments into streams, lakes, and rivers; and improvements in air quality (Lal et al. 2003). The estimated

POLICIES RELATING TO SOIL CARBON SEQUESTRATION

Attention to the contributions of grazing lands to GHG emissions and mitigation is warranted because of their large area and the focus of governments at all levels—international and domestic—to develop and implement mandatory GHG emissions reductions policies to combat global climate change. Soil C management is internationally recognized as being consistent with landscape-level land-management policies that provide multiple societal benefits (Kraxner et al. 2007). The benefits include improved

USDA PROGRAMS

USDA conservation policies and farmland protection and restoration programs for grazing lands to retain and enhance soil C stocks are included in existing public efforts to achieve soil C sequestration. The 1981 Farm Bill (formally the Agriculture and Food Act of 1981) laid the groundwork for the first federal farmland protection program and required an assessment of the impact of federally funded programs that converted farmland to nonagricultural uses. The 1996 Farm Bill established the

THE 2008 FARM BILL

The recently enacted Food, Conservation and Energy Act of 2008, i.e., the 2008 Farm Bill, contains new programs to help quantify environmental and societal benefits from grazing-land improvements. These conservation programs enable agricultural producers to increase soil C in grazing-land soils, but presently, there are no regional or state mandatory policies that recognize soil C sequestration by grazing lands as a certifiable offset. However, because of their large areas in every region,

OTHER US LEGISLATION

The 110th Congress devoted increased attention to global climate change through mandatory, national GHG emissions reductions policies and programs. In the Senate, mandatory cap-and-trade legislation was introduced by Senators Joseph Lieberman (I-CT) and John Warner (R-VA) and achieved prominence as the first such bill to pass through its full committee of jurisdiction (S.2191, America’s Climate Security Act of 2007; Banks 2008). S.2191 passed the full Senate Environment and Public Works

FUTURE PUBLIC POLICIES

Important to promoting soil C management on grazing lands is its inclusion as a category of eligible emissions reductions offsets within mandatory emissions reductions policies. Soil carbon management has multiple societal benefits, including GHG emissions reductions in cap-and-trade programs, as an offset to provide cost savings in terms of reducing GHG emissions at a net savings to society (McKinsey 2007), and by reducing compliance costs for capped sectors and for the cap-and-trade system (

SOIL CARBON CREDITS IN GHG MARKETS

Grazing lands can provide valuable GHG emissions reductions and enhanced soil C sinks on behalf of society as a means of providing a source of low-cost, readily implemented, high-impact offset credits. Offset credits are a viable, important cost-containment mechanism for cap-and-trade approaches to mandatory GHG emissions reductions programs. Virtually every major economic analysis of how the US can begin to slow, stop, and reverse its growing emissions of GHG relies upon soil C sinks as a

FUTURE USDA PROGRAMS

Market-based incentives in support of agricultural conservation activities and terrestrial sequestration on public and private lands, including grazing lands, can provide income-generation potential to accomplish a suite of environmental, natural resource, and ecosystem benefits enjoyed by society at large as well as the agricultural sector. Historically, federal funding for agricultural conservation programs has been growing. A historical analysis of farm program spending (Zulauf 2005)

RESEARCH RECOMMENDATIONS

The value and synergy between carbon management and soil C content should be a “cementing element” driving various international and federal land-use and environmental policies (Kimble et al. 2007; Kraxner et al. 2007). Analyses of how to harmonize agricultural land management, including GHG and soil C management policies, with other agricultural and climate-change mitigation policies should be further developed at the landscape scale in order to avoid duplication and unintended consequences

MANAGEMENT IMPLICATIONS

Management practices are highly important to maintain, utilize, and improve the remaining and/or additional grazing lands within each region and state. The goal is to protect soil, water, and air quality, and wildlife habitat to which existing stocks of and sequestration of SOC contribute importantly. Rates of SOC sequestration vary with climate, soil, and management. Planning efforts to improve management are likely to have a greater impact if done at the watershed, state, or local level and

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    Grasslands represent approximately one-third of the world's terrestrial ecosystems providing numerous ecosystems services including carbon sequestration (Ellis and Ramankutty, 2008; Piao et al., 2020; Bai and Cotrufo, 2022). Grassland ecosystems are estimated to contain about 10 %–30 % of the earth's soil organic carbon and play crucial roles in the global carbon balance (Piao et al., 2009; Follett and Reed, 2010). China's grasslands cover about 6 %–8 % of the areas and 9 %–16 % of carbon stocks of the global grasslands, respectively (Ni, 2002; Fan et al., 2008; Tang et al., 2018).

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This publication is based upon work partially supported by the Agricultural Research Service (ARS) under the ARS GRACEnet (Greenhouse Gas Reduction through Agricultural Carbon Enhancement Network) Project.

Mention of a proprietary product is not an endorsement of the product by the Agricultural Research Service of US Department of Agriculture or the authors and does not imply its approval to the exclusion of other products.

This publication was made possible through support provided to the Global Livestock Collaborative Research Support Program by the Office of Agriculture, Bureau for Economic Growth, Agriculture and Trade, United States Agency for International Development under terms of Grant No. Grant No. PCE-G-00-98-00036-00. The opinions expressed herein are those of the author(s) and do not necessarily reflect the views of the USAID.

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