Agriculture is a source of greenhouse gas (GHG) emissions, which many scientists agree are contributing to observed climate change. Agriculture is also a "sink" for sequestering carbon, which partly offsets these emissions. Second, the report describes the types of land management and farm conservation practices that can reduce GHG emissions and/or sequester carbon in agricultural soils, highlighting those practices that are currently promoted under existing voluntary federal agricultural programs. Source of National Estimates

Estimates of GHG emissions and sinks for the U.S. agriculture sector presented in this report are the official U.S. estimates of national GHG emissions and carbon uptake, as published annually by the U.S. Environmental Protection Agency (EPA) in its Inventory of U.S. Greenhouse Gas Emissions and Sinks . This aggregation is intended to illustrate agriculture's contribution to national GHG emissions and to contrast emissions against estimates of sequestered carbon. Agricultural sources of CH 4 emissions mostly occur as part of the natural digestive process of animals and manure management in U.S. livestock operations. These estimates do not include emissions associated with on-farm energy use and forestry activities. Higher feed effectiveness is associated with lower emissions. Land Use and Forestry Emissions

Land use and forestry activities account for less than 1% of total estimated GHG emissions in the United States ( Table 1 ). Improved Soil Management

Options to reduce nitrous oxide emissions associated with crop production include improved soil management, more efficient fertilization, and implementing soil erosion controls and conservation practices. Agricultural Carbon Sinks

			Carbon Loss and Uptake

Agriculture can sequester carbon, which may offset GHG emissions by capturing and storing carbon in agricultural soils. Other Land Use and Forestry Sequestration

These estimates do not include estimates for the forestry sector, or sequestration activities on forested lands or open areas that may be affiliated with the agriculture sector. Congressional Action

		Energy and Climate Legislative Proposals

Congress is currently considering a range of energy and climate policy options. In general, the current climate proposals would not require GHG emission reductions in the agriculture and forestry sectors. However, if enacted, provisions in these bills could potentially raise farm input costs for fossil fuels, fertilizers, energy, and other production inputs. These higher costs could potentially be offset by possible farm revenue increases should farmers participate in carbon offset and renewable energy provisions that are part of this legislation. For example, within cap-and-trade proposals being debated in Congress are provisions that could provide tradeable allowances to certain agricultural industries, and provisions that could establish a carbon offset program for domestic farm- and land-based carbon storage activities. In addition, the renewable energy provisions contained in these bills could potentially expand the market for farm-based biofuels, biomass residues, and dedicated energy crops. These and related bills and issues are currently being debated in Congress. ); Effectiveness , the success of the mitigation practice will depend on the type of practice, how well implemented and managed by the farmer or landowner, and the length of time the practice is undertaken; Additionality/Double Counting , given that some of the activities generating offsets would have occurred anyway under a pre-existing program or practice, and thus may not go beyond business as usual (BAU); and/or given that some reductions may be counted by another program (e.g., attributable to other environmental goals under various farm conservation programs) or toward more than one GHG reduction target; and Leakage , given that reductions in one place could result in additional emissions elsewhere.
The agriculture sector is a source of greenhouse gas (GHG) emissions, which many scientists agree are contributing to observed climate change. Agriculture is also a "sink" for sequestering carbon, which might offset GHG emissions by capturing and storing carbon in agricultural soils. The two key types of GHG emissions associated with agricultural activities are methane (CH4) and nitrous oxide (N2O). Agricultural sources of CH4 emissions mostly occur as part of the natural digestive process of animals and manure management at livestock operations; sources of N2O emissions are associated with soil management and fertilizer use on croplands. This report describes these emissions on a carbon-equivalent basis to illustrate agriculture's contribution to total national GHG emissions and to contrast emissions against estimates of sequestered carbon.
Emissions from agricultural activities account for 6%-8% of all GHG emissions in the United States. Carbon captured and stored in U.S. agricultural soils partially offsets these emissions, sequestering about one-tenth of the emissions generated by the agriculture sector, but less than 1% of all U.S. emissions annually. Emissions and sinks discussed in this report are those associated with agricultural production only. Emissions associated with on-farm energy use or with food processing or distribution, and carbon uptake on forested lands or open areas that might be affiliated with the farming sector, are outside the scope of this report.
Most land management and farm conservation practices can help reduce GHG emissions and/or sequester carbon, including land retirement, conservation tillage, soil management, and manure and animal feed management, among other practices. Many of these practices are encouraged under most existing voluntary federal and state agricultural programs that provide cost-sharing and technical assistance to farmers, predominantly for other production or environmental purposes. However, uncertainties are associated with implementing these types of practices depending on site-specific conditions, the type of practice, how well it is implemented, the length of time a practice is undertaken, and available funding, among other factors. Despite these considerations, the potential to reduce emissions and sequester carbon on agricultural lands is reportedly much greater than current rates.
Congress is currently considering a range of energy and climate policy options. In general, the current climate proposals would not require GHG emission reductions in the agriculture and forestry sectors. However, if enacted, provisions in these bills could potentially raise farm input costs for fossil fuels, fertilizers, energy, and other production inputs. These higher costs could potentially be offset by possible farm revenue increases should farmers participate in carbon offset and renewable energy provisions that are part of this legislation. For example, within cap-and-trade proposals being debated in Congress are provisions that could provide tradeable allowances to certain agricultural industries, and provisions that could establish a carbon offset program for domestic farm- and land-based carbon storage activities. In addition, the renewable energy provisions contained in these bills could potentially expand the market for farm-based biofuels, biomass residues, and dedicated energy crops. These and related bills and issues are currently being debated in Congress.