Tuesday, November 6, 2007
204-8
Soil Organic Carbon Evolution in Soils of Contrasting Drainage Under Continuous Corn as Influenced by Tillage.
Silvia Mestelan, ARGENTINA,Univ. Nacional, Facultad de Agronomia / OSU, 2021 Coffey Road - 426 Kottman Hall, Columbus, OH 43210, Warren A. Dick, Environment and Natural Resources, Ohio State University - OARDC, 1680 Madison Avenue, Wooster, OH 44691, Neil Smeck, Ohio State University - Columbus, 414E Kottman Hall-Sch Natl Res, OH State Univ. 2021 Coffey Rd, Columbus, OH 43210, and Jeanne Durkalski, Soil Science, The Ohio State University, OARDC, Wooster, OH 44691.
Long-term plots (44 yr) under no till (NT) and plow till (PT) cultivated continuously with corn in well and poorly drained sites (Wooster and Hoytville, Ohio) were sampled on a decadal basis to track changes in soil nutrient dynamics and soil physicochemical properties. Study of the evolution of soil organic C (SOC) fractions under these tillage systems is significant to understanding SOC accrual or oxidation. During the four decades of study, a gradual increase was observed in SOC in the surface layer (0-22,5 cm) in NT (38.8 g kg-1) relative to PT (19.7 g kg-1) for Hoytville; the respective SOC values for Wooster soil were 34.7 g kg-1 for NT and 12.3 g kg-1 for PT. The depth of C accumulation extends to about 50 cm for Wooster and 22 cm for Hoytville and has progressively increased since establishment of the tillage treatments. Increased macroporosity, bioturbation, and aggregation in NT are associated with and promote incorporation of SOC. The potential to increase the C pool is higher in Wooster than in Hoytville due to a greater differential between corn yields with NT and PT (+1000 Mg ha-1 in Wooster, -800 Mg ha-1 in Hoytville). Long-term maintenance of NT, compared to PT, led to an accumulation of organic matter and a sustained ability to support high grain yields in the soil with highest susceptibility to erosion (Wooster), suggesting that NT management can sustain or even enhance soil quality at the Wooster site.