Greenhouse gas emissions arise from a variety of sources including methane from rice paddies and livestock, nitrous oxide (N2O) from cultivated soils and feedlots, and CO2 from the cultivation of virgin agricultural lands and intensive production methods. Farmers have a variety of adaptations open to them for improving the management of agricultural systems. These include rotating crops, selecting crops and crop varieties, applying irrigation water efficiently, nutrient budgets that include all nutrient sources, livestock waste management, and conservation tillage. In addition, agriculture can reduce the amount of atmospheric CO2 through conservation practices, biomass production, tree-planting, and similar programs that sequester significant amounts of carbon and replace fossil fuels.
The United States Department of Agriculture (USDA) and the Environmental Protection Agency (EPA) recognize that there is often site-specific, regional, and national variability in the selection of appropriate management practices. The general management measures defined as Best Management Practices that have been developed for use by farmers to address non-point source pollution also affect CO2 and other greenhouse gas emissions. Best Management Practices are defined in USDA's Field Operations Technical Guide and are recommended by the Department for use as components of Resource Management Systems, Water Quality Management Plans, and Agricultural Waste Management Systems. Many farms have already developed management plans that contribute to reducing non-point source pollution and greenhouse gas emissions and either have implemented these plans or are in the process of implementing them.
Prices and related market changes also guide farmers in land use decisions and the selection of crops and production practices. Thus, patterns of food production respond not only to biophysical changes in crop and livestock productivity brought about by climate and technological change, but also to changes in agricultural management practices, crop and livestock prices, the cost and availability of inputs, and government policies. In the longer term, adaptations include the development and use of new crop varieties that offer advantages under changed climates or investments in an irrigation infrastructure as insurance against potentially less reliable rainfall. The extent to which opportunities for adaptations are realized depends upon a variety of factors such as research, information flow, access to capital, and the flexibility of government programs and policies.