SOIL EROSION VARIES DURING THE CROP YEAR

Temporal variations in erosion rates and sediment size distributions were evaluated as affected by crop growth, soil condition, continued storm rainfall, and prior land use. Erosion decreased by 90% between cotton emergence and post-harvest, largely due to increased plant canopy and surface residue cover. However, soil changes were also important, including strong evidence that susceptibility to erosion decreased during the crop year. Erosion of most bare, tilled soils decreased as storm rainfall continued, with the greatest change for the more erodible soils. Tilled woodland soil was only half as erodible as tilled soil cropped to continuous cotton, and tilled pasture was midway between. Sediment size distributions changed little due to crop stage, cover, or continued storm rainfall, but they were affected by land use history.