Saturday, 15 July 2006

Intermittent Chisel Tillage Effects on Soil Organic Carbon and Total Nitrogen Relative to Continuous No-Till and Chisel Plow Systems.

Rex A. Omonode1, Anita Gal1, Diane E. Stott2, Scott Abney3, and Tony J. Vyn4. (1) Purdue Univ, Dept of Agronomy, 994 Edgerton Street, West Lafayette, IN 47906, (2) USDA-ARS National Soil Erosion Research Laboratory, 275 S Russell St, West Lafayette, IN 47907-2077, (3) Purdue Univ, Dept of Botany and Plant Pathology, 915 W.State St, West Lafayette,, IN 47907-2054, (4) Purdue Univ, Agronomy Dept, 915 W. State Str., West Lafayette, IN 47907-2054

For various reasons, North American crop farmers are more likely to practice limited-duration no-till than continuous no-till. Little is known about effects of short-term no-till on organic Carbon (C) and total Nitrogen (N) relative to continuous no-till and conventional-till systems. A field experiment was initiated in 1980 to study the effects of continuous No-Till (NT), continuous Chisel Plow (CP), and moldboard plow in continuous corn and soybean-corn rotations on dark prairie soil. In 1996, the moldboard treatments were split into a short-term no-till (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 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 years totaled 151 Mg ha-1 in continuous NT, but just 108 Mg ha-1 in continuous CP. ST-NT and STI-CP systems resulted in 26 and 21 Mg ha-1, respectively, more soil C than CP. Total N storage was similar for NT 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 years) followed by short-term (6-7 year) no-till or intermittent chisel was generally superior to continuous chisel plowing (24 years) in soil C and N contents.

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