LONG TERM SEDIMENT YIELD AND MITIGATION IN A SMALL SOUTHERN PIEDMONT WATERSHED

Southern Piedmont lands suffer moderate to severe erosion when farmed under single-crop,conventional till systems consisting of moldboard plowing, disking or harrowing. This is primarily due to high soil erodibility, high energy spring-summer storms, low residue cover, and poor management thctors. A winter season with no crop often leaves soil unprotected from rainfall impacts.Conservation cropping systems that minimize tillage and leave a growing crop and crop residues on the surface both in summer and winter protect soil from erosive effects and sustain productivity. In this paper we present and discuss 26-years of soil loss, runoff and residue production data from a 2.71 ha catchment typical of small Southern Piedmont watersheds. The catchment was first managed in conventional tillage system of summer soybean (Glycine max (L.) Merrill) and winter fallow from 1972 to 1974. It was then converted to conservation cropping systems of summer soybean, sorghum (Sorghuim bicolor (L.) Moench), or cotton (Gossypium hirsutum (L.)) and winter barley (Hordeum vulgare (L.)), wheat (Triticum aestivum (L.)), or clover (Trdolium incarnatum (L.)) which have continued to the present. Conservation cropping systems had immediate and residual effects in controlling erosion and runoff in both summer and winter. Destructive soil erosion, from high energy storms was significantly reduced. Residue production increased from about 2 Mg ha-1 yr-1 under conventional tillage to 9.88 Mg ha-1 yr-1 under conservation cropping systems over 20 years.