Islam, K.Rafik. (The Ohio State University, 1864 Shyville Road, Piketon, OH, 45661;

Phone: 740-289-2071; Fax: 740-289-4591; Email: islam.27@osu.edu)

Biological, Chemical and Physical Sequestration of Soil Carbon in Response to Tillage

K.R. Islam *, A. Sundermeier

Increasing soil carbon sequestration through conservation management practices can improve environmental quality. To evaluate the impact of no-till (NT) continuous corn system on carbon sequestration, composite soil core samples at 0-7.5, 7.5-15, 15-22.5 and 22.5-30 cm depth were collected from 2, 8, and 40 yr no-till and their adjoining conventionally-tilled (CT) replicated plots at the Northwest Branch of the Ohio Agricultural Research and Development Center in Wood County, Ohio in fall of 2004. The soil at the experimental location is Hoytville clay loam (Fine, illitic, mesic Mollic Epiaqualfs), which is a deep very poorly drained soil with moderately slow permeability. Soil samples were processed and analyzed for concentration and masses of biologically (e.g. microbial biomass and active C), chemically (e.g. passive, extractable, and total organic C) and physically defined (e.g. particulate organic C) C pools and basic soil properties. The concentration and mass of microbial biomass, active, extractable, particulate and total organic carbon pools increased significantly in NT soil over time compared to CT soil. Temporal effect tillage had more pronounced on active, microbial biomass and particulate organic carbon than total organic content. Variations in C pools under different tillage systems were more pronounced at surface depth (0-7.5 cm) of soil. Combined over depth 0-30 cm), the profile wise storage of microbial biomass, active, particulate and total organic C pools varied significantly in response to the length of NT operation. Among the C pools, microbial biomass and active C changed consistently in response to tillage operations. Significantly greater concentration and mass of various C pools in NT soils compared to CT soils are possibly due to surface deposition of crop residues, less disturbance, greater physical protection over time.