Soils Policy: Resource Conservation, Land, and Greenhouse Gas Reductions
The reduction of greenhouse gas (GHG) releases from land-based sources into the atmosphere due to human practices can achieve multiple important environmental and energy goals. Strategies to reduce, reuse, and recycle materials prevent the creation of greenhouse gases that lead to global warming by minimizing the need to dispose of biologically-degradable wastes that are disposed of in landfills or incinerated. Land-based initiatives related to forestry, agriculture, and waste management, which focus on reducing the release of carbon dioxide, methane, and nitrous oxides after they have been created, can reduce emissions to the atmosphere and protect sensitive lands from degradation, improve the productivity of soils for agriculture, and minimize adverse environmental impacts of waste disposal. For example, practices that protect soils used in agriculture can prevent the release of carbon sequestered in soils. When wastes are disposed of in landfills, actions that capture landfill methane gas released in their decomposition both can prevent emissions that contribute to global warming and provide an additional source of energy. Third, land-based carbon sequestration strategies that prevent the loss of carbon into the atmosphere may help buy time for nations to develop and implement renewable energy strategies to combat global warming. This fact sheet is not comprehensive; rather, it provides a starting point for readers interested in investigating this topic.
- Greenhouse Gases and Land
- Strategies for Greenhouse Gas Reduction
- Policy Directions in Europe and Abroad
- Some U.S. Activities and Additional Resources
- Other Federal Agencies
Greenhouse Gases and Land
Release of greenhouse gases into the atmosphere influences the global climate by trapping infrared radiation and heat that otherwise would escape back into space. In recent centuries, especially with the Industrial Revolution, human activities increasingly have influenced the character of greenhouse gases in the atmosphere. The atmospheric concentration of carbon dioxide, for example, has increased by about 30% since the 18th century, while levels of methane have more than doubled.
The biological carbon cycle involves absorption, conversion, and release of carbon by living organisms through photosynthesis, respiration, and decomposition. These natural processes remove billions of tons of carbon dioxide from the atmosphere annually and release carbon dioxide back into the atmosphere in roughly equal amounts. Globally, soils contain about three times more carbon (in the form of sequestered soil organic carbon) than is present in vegetation. In addition to natural chemical and biological processes, carbon is released from soils over time when, because of human agricultural practices and deforestation, soil organic matter previously protected from microbial action decomposes more rapidly than would occur naturally. Conversely, soil organic carbon stocks can be revitalized, e.g., when croplands are converted to grasslands, forest lands, or natural ecosystems.
Methane is over twenty times as potent a GHG as carbon dioxide. Soil sequesters methane over time. Human activities, e.g., conversion of woodland to agricultural land, the production of natural gas, and coal mining, however, can accelerate the release of methane from land. Landfilling or combustion of waste both create and release methane into the atmosphere. Landfills, which produce methane when organic matter is broken down by bacteria, are classified as the second largest human-made source of methane in the U.S.
A GHG that is over three hundred times more potent that carbon dioxide, nitrous oxide is released naturally from bacteria in soils. Human activities, in particularly the application of nitrogen-based fertilizers which provide nutrients for crops, also are responsible for the release of nitrous oxide into the atmosphere from soils. The heavy use of synthetic nitrogen fertilizers in crop production typically results in significantly more nitrous oxide emissions from agricultural soils than occurs with less intensive, low-tillage techniques. Other sources of nitrous oxide releases are animal manure management, sewage treatment, mobile and stationary combustion of fossil fuels, adipic acid production, and nitric acid production.
Strategies for Greenhouse Gas Reduction
Materials Conservation and Recovery
Waste prevention, recycling, and reuse are important public policy strategies for reducing greenhouse gas emissions through better materials and land management. These alternatives to using virgin materials save energy and reduce associated greenhouse gas emissions. Manufacturing goods from recycled materials, for example, typically requires less energy and results in less associated carbon dioxide emissions than extracting, transporting, and processing raw materials and manufacturing products using virgin materials.
- waste prevention and recycling of paper products reduce the need for virgin timber, allowing standing trees to sequester carbon after removing carbon dioxide from the atmosphere
- greenhouse gas emissions from the combustion of waste are reduced when recycling and waste prevention divert materials from incinerators
- methane emissions from landfills that occur when wastes decompose are prevented when organic wastes are diverted from landfills and reduced when landfill gas is collected for reuse
- Although composting organic materials such as food scraps and yard waste may result in the release of some non-biogenic carbon dioxide associated with transporting and turning the compost, much of the carbon contained in organic materials is returned and stored in the soil through composting and therefore not released into the atmosphere.
Agricultural practices increase soil carbon sequestration through biological processes that improve soil quality and prevent the loss of greenhouse gases from depleted soils. These practices include timber management (e.g., forest protection and reforestation). Minimum-till and no-till farming, more extensive use of cover crops, and mixed crop-livestock farming. In protecting existing soil from disturbances and adding organic materials to the land, these strategies both can mitigate the adverse impacts of greenhouse gas releases and provide the soil fertility necessary for sustainable agronomy. Practices that improve soil structure, conserve water, enhance soil fauna activity, and limit the presence of crop pests, including the use of organic soil supplements, also reduce the need for synthetic nitrogen fertilizers - the production of which is responsible for the release of nitrous oxide into the atmosphere.
Carbon Capture and Storage
Carbon capture and storage (CCS) encompasses a number of technologies designed to capture carbon and prevent the release into the atmosphere of carbon dioxide from point sources, such as power plants and industrial facilities. Use of these technologies may help slow the build up of carbon dioxide in the atmosphere by mitigating the impact of emissions and help to "buy time" for strategies that prevent the creation of greenhouse gases. Technological, energy, environmental, and economic issues pose potential barriers to the implementation of land-based carbon capture and storage alternatives:
- Geological sequestration. Carbon dioxide can be captured at coal-fired power plants and other industrial facilities using CCS (CCS) technology for injection underground into porous rock formations
- Mineral carbon sequestration. Mineral carbon dioxide sequestration uses a technology involving the reaction of carbon dioxide with metal cations in silicate minerals to form solid carbonate minerals.
Policy Directions in Europe and Abroad
The European Commission's CLIMSOIL Study in December 2008 addressed the importance of soil policy in the debate over climate change. The report concludes that land use change poses the most significant risk for carbon loss from soil in the longer term for EU States, and that the most effective option for managing soil carbon to mitigate global climate change is to preserve existing stocks of carbon in soils, especially in peat and other soils with high organic content. The CLIMSOIL Study has been used to support the EU's Soil Thematic Strategy and a proposed soil framework directive to protect and improve soils. A number of important EU resources exist to provide information on soils and soil management. The EU Soil Portal makes available maps of organic carbon content in the surface horizon of soils in Europe. The EU European Soil Data Center (ESDAC) is an important repository for soil-related data in Europe.
The European Environment Agency actively promotes consumer choices that minimize waste and recycling and reuse to reduce green house gas emissions. A European Commission study titled, "Waste Management and Climate Change" assesses the climate change impacts of options for municipal solid waste (MSW) management in the EU and concludes that source separation and composting or recycling of biodegradable wastes have the greatest benefit in terms of greenhouse gas reductions relative to other materials management alternatives. "Waste Management Options and Climate Change" also highlights the benefits of improved gas management at landfills to capture releases of greenhouse gases produced from waste decomposition. Consistent with these conclusions, a green paper was developed in 2008 to address the management of biodegradable waste in the EU and the need for uniform quality criteria for composts to facilitate the reintroduction of organic substances and nutrients into soils.
Also in 2008, the European Commission proposed a directive to create an enabling regulatory framework and support demonstration projects for the environmentally-safe capture and geological storage of carbon dioxide. In September 2009, the EU pledged over one million euros to fund six carbon capture and storage projects.
Food and Agriculture Organization (FAO) of the United Nations
FAO publications on climate change highlight the connections between climate change and agriculture. " Managing Soil Carbon to Mitigate Climate Change: A Sound Investment in Ecosystem Services (PDF)" summarizes actions with respect to soil carbon management proposed by sixty delegates from America, Africa, Asia, Australia, and Europe at an international Conservation Agriculture Carbon Offset Consultation Held in October 2008. A 2009 report titled, "Organic Agriculture and Carbon Sequestration (PDF)" addresses the importance of agricultural practices generally and organic agriculture in particular for sustainable terrestrial carbon sequestration. Although agriculture is not currently part of the United Nations carbon offset program, and although practical questions (e.g., related to measurement and certification) about implementing such policies would need to be addressed, the paper identifies opportunities to include agriculture in carbon trading schemes.
Some U.S. Activities and Additional Resources
Environmental Protection Agency (EPA)
- Materials management. EPA promotes improved materials management approaches to reduce GHG during the entire life cycle of materials. In September 2009, EPA issued the report, Sustainable Materials Management: the Road Ahead, and is moving ahead to support demonstration projects recommended Measurement tools (e.g., the Waste Reduction Model), help solid waste planners and organizations track and voluntarily report greenhouse gas emissions reductions from waste management practices such as recycling, demonstrate the quantitative benefits of smart waste management. EPA is working in conjunction with agencies at all levels of government to undertake actions that reduce waste-related greenhouse gas emissions. Wastewise is a voluntary EPA program through which organizations save money and minimize the amount of waste placed in landfills by reducing the creation of costly municipal solid waste and select industrial wastes.
- Methane. EPA's Landfill Methane Outreach Program (LMOP), a voluntary assistance program to help reduce methane emissions from landfills, encourages the recovery and beneficial use of landfill gas (LFG) as an energy resource. AgSTAR is a joint EPA, U.S. Department of Agriculture (USDA), and U.S. Department of Energy (DOE) program to encourage the use of methane recovery (biogas) technologies at confined animal feeding operations that manage manure as liquids or slurries. The Coalbed Methane Outreach Program (CMOP) is a voluntary EPA program to reduce methane emissions from coal mining activities, and the Agency's Methane to Markets Partnership is an international initiative to advance cost-effective, near-term methane recovery and use as a clean energy source. EPA's voluntary Natural Gas STAR Program encourages oil and natural gas companies—both domestically and abroad—to adopt cost-effective technologies and practices that improve operational efficiency and reduce methane emissions.
- Green remediation. EPA works with private and public partners to foster the use of best management practices (BMPs) for green remediation at contaminated sites throughout the United States by documenting the state of BMPs, identifying opportunities for improvement, establishing a community of BMP practitioners, and developing mechanisms and tools to help site clean up and reuse stakeholders make informed decisions about green clean-up strategies.
- Carbon capture and storage. Carbon capture and storage (i.e., through agriculture and forestry or through geologic sequestration) can prevent GHG emissions to the atmosphere. Key components of success in geological sequestration include ensuring that it is safe and will achieve the long-term goal of isolating CO2. EPA's Underground Injection Program regulates underground injection of CO2 and other fluids under the Safe Drinking Water Act (SDWA).
Other Federal Agencies
- Department of Energy (DOE). DOE initiatives related to carbon sequestration include core research, demonstration projects, and regional partnerships. For example, the National Energy Technology Laboratory (NETL) is helping to develop technologies to capture, separate, and store carbon dioxide, and FutureGen is a public-private partnership to design, build, and operate the world's first coal-fueled, near-zero emissions power plant.
- Department of Agriculture (USDA). USDA GRACEnet (Greenhouse Gas Reduction through Agricultural Carbon Enhancement Network) is a research program that has been initiated by the USDA’s Agricultural Research Service (ARS) to identify and further develop agricultural practices that will enhance carbon sequestration in soils. ARS also studies the role of no-till and reduced tillage practices in reducing atmospheric greenhouse gas concentrations by storing more carbon in soil. The U.S. Forest Service provides data, information, and tools to help managers and policymakers address the role of forests and grasslands in climate change.
- Department of the Interior/U.S. Geological Survey (USGS). The goal of global change research at USGS is to improve knowledge and understanding of the Earth’s past and present climate and environment. The USGS assesses biological carbon stocks and forest biomass carbon sequestration capacity in the United States. For example, the Deep Soil Carbon Project focuses on the state of deep soil organic carbon storage in Alaska and the effects of climate change of carbon storage.
Ten U.S. federal agencies and departments support the United State Carbon Cycle Science Program, which aims to study and quantify the many complex relationships involving the Earth's carbon reservoirs and climate.