Short-term versus continuous chisel and no-till effects on soil carbon and nitrogen

various reasons, North American crop farmers are more likely to practice limited-duration no-till than continuous no-till (NT). Little is known about effects of short-term no-till (ST-NT) on organic C and total N relative to NT and conventional-till systems. A field experiment was initiated in 1980 to study the effects of NT, chisel plow (CP), and moldboard plow in continuous corn (CC; Zeamays L.) and soybean (Glycinemax. L.)-corn (SC) rotations on dark prairie soil. In 1996, the moldboard treatments were split into a ST-NT subplot and an intermittently chisel-plowed (STI-CP) subplot that was chiseled only before corn. In 2003, soil samples were taken incrementally to the 1.0-m depth from NT, CP, ST-NT, and STI-CP plots. Soil C and N accumulation was unaffected by rotation system at any depth interval. Tillage treatments significantly affected soil C and N concentrations only in the upper 50 cm. On an equivalent soil mass basis, C storage to 1.0 m after 24 yr totaled 151 Mg ha(-1) in continuous NT, but just 108 Mg ha(-1) in continuous CP. Short-term no-till and STI-CP systems resulted in 26 and 21 Mg ha(-1), respectively, more soil C than CP. Total N storage was similar for NIT and ST-NT systems, but was significantly lower (4 Mg ha(-1) less) with CP. Our results suggest that the combination of moldboard plowing (17 yr) followed by short-term (6-7 yr) no-till or intermittent chisel was generally superior to continuous chisel plowing (24 yr) in soil C and N contents.