A Conservation Tillage-Cropping Systems Study in the Northern Great Plains of the United States
Soil erosion is recognized as a serious threat to sustainable agriculture and, in some areas of the world, to the production of food and fiber to meet human needs. In the semiarid northern Great Plains soil losses, predominantly by wind and to a lesser extent by water erosion, exceed 5 tons per acre annually on about 50% of the cropland. Soil erosion in the northern Great Plains is deemed to diminish soil productivity by also diminishing soil organic matter content. The cropping systems, tillage, and N-fertilizer treatments were initiated in 1984 and soil samples by increment depths were again taken in the spring of 1991 after 7 years of treatments. After 7 years in the crop-fallow system, tillage and N-fertilizer treatments did not have much influence on bulk density, total soil N, or soil C. Amount of crop residue produced and returned to the land is the major source of organic C input back into the soil.