Sustaining soil quality with legumes in no-tillage systems

Tillage, cropping system, and cover crops have seasonal and long-term effects on the nitrogen (N) cycle and total soil organic carbon (C), which in turn affects soil quality. This study evaluated the effects of crop, cover crop, and tillage practices on inorganic N levels and total soil N, the timing of inorganic N release from hairy vetch and soybean, and the capacity for C sequestration. Cropping systems included continuous corn (Zea mays L.) and stalk residue, continuous corn and hairy vetch (Vicia villosa Roth), continuous soybeans (Glycine max L.) plus residue, and two corn/soybean rotations in corn alternate years with hairy vetch and ammonium nitrate (0, 85, and 170 kg N ha-1). Subplot treatments were moldboard plow and no tillage. Legumes coupled with no tillage reduced the N fertilizer requirement of corn, increased plant-available N, and augmented total soil C and N stores.