Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: July 31, 2000
Publication Date: July 31, 2000
Technical Abstract: Particulate organic C may be an important intermediate stage of decomposition in organic matter between biologically active and chemically inert extremes that is indicative of medium-term changes in soil C sequestration. My objectives were to (1) determine the depth distribution of total and particulate organic C, (2) determine the effect of long-term pasture management on total and particulate organic C pools, and (3) evaluate particulate-to-total organic C and particulate organic C-to-N ratios to determine root-derived contributions to soil organic C. Both total and particulate organic C decreased with soil depth (e.g., particulate organic C was 30, 6, 3, and 1 g/kg at depths of 0-2.5, 2.5-7.5, 7.5-15, and 15-30 cm, respectively). Grazed pastures sequestered more soil organic C than hayed and unharvested pastures. Fertilization increased total and particulate organic C. An annual cropping system (i.e., low root accumulation) had significantly lower ratios of particulate-to-total organic C, especially with increasing soil depth, than a forested system (i.e., high root accumulation), suggesting that the particulate-to-total organic C ratio could reflect contributions of roots to soil C sequestration.