Crop production systems to control erosion and reduce runoff from upland silty soils

Soil erosion remains the most significant threat to long-term agricultural sustainability. In order to determine if highly erodible silty upland soils could be row-cropped while conforming to the conservation provisions of th e Food Security Act, we measured natural-rainfall runoff and soil loss for sir years from eight alternative cropping systems on sixteen 4% slope plots and three small watersheds in north Mississippi. Several conservation crop ping systems slightly reduced runoff and greatly decreased erosion on these soils. On erosion plots, no-till for soybean, corn, or sorghum reduced soi l loss by more than 80% and no-till for cotton by more than 70% as compared to conventionally tilled soybean. Ridge-till was more than twice as erodib le as no-till, while no-till soybean double-cropped with wheat was least er odible of the eight systems studied. On small watersheds, annual sediment y ield ranged up to about 30 t/ha for conventional tillage soybean with buffe r strips and grassed waterways but, after the first year never exceeded 1 t /ha for no-till soybean. However; no-tillage alone was not adequate to cont rol concentrated-flow headcuts. Most conservation systems decreased runoff by at least 10%. No-till sorghum or corn with a vetch cover crop generally decreased runoff most, and double-cropped soybean-wheat had less than 75% o f the runoff of conventional soybean. Greatest reductions occurred during y ears of higher runoff amounts. Runoff per unit of area from the watersheds was much greater than from comparable erosion plots, indicating that extrap olation of plot data to field areas merits careful consideration of their r elative soil and topographic characteristics. This research demonstrated th at several no-tillage cropping systems can keep erosion below tolerable lim its, reduce runoff somewhat, and be economically profitable. When combined with complementary conservation practices such as waterways and grass hedge s, they provide methods for achieving both effective conservation and susta inable production when intensively cropping erodible upland soils of the so uthern United States.