GLOBAL CLIMATE-CHANGE, UNITED-STATES AGRICULTURE, AND CARBON-DIOXIDE

What should U.S. agriculture do to adapt for possible climate change and what can it do to reduce greenhouse gas emissions? An evaluation indicates that, unless there is a decline of about one-fourth in total crop yields, the U.S. land resource base will be adequate and food security can be met. The impacts of climate change on individual crop production regions are hard to predict, however, and may be either negative or positive. The assumption must be made that agriculture faces an uncertain future and, therefore, must rely upon experience, adoption of proven technologies, development of new technologies, and improved husbandry of land, water, and energy resources. Carbon dioxide, one of the greenhouse gases, can be emitted, as well as sequestered, in large amounts by agriculture. Agriculture has a great opportunity to help mitigate climate change by stashing CO2 as C in soil and vegetation and by displacing fossil fuels. Practices requiring good agricultural husbandry, which should be implemented anyway, can be quite effective for sequestering C. For cropland, these practices include building soil organic matter levels, improving soil fertility, and growing more food on less land. Carbon pools are maintained, restored, and enlarged on croplands by increased use of conservation tillage, improved use of animal and other wastes, minimized dryland fallowing, and preservation of marginal lands. On forestlands, reforestation, forestation (including tree planting on conservation reserve program land), and improved forest harvesting practices maintain and enlarge C-pools. Preservation of wetlands does much to maintain C-pools. Collectively, these practices can potentially offset not only the CO2 emissions from U.S. agriculture, but also part of that from U.S. sources outside of agriculture.