Tuesday, 8 November 2005
19

This presentation is part of: SOM, C Dynamics, and GHG Emissions: II

Management Effects on Soil Organic Carbon in the Piedmont and Coastal Plain.

Hector J. Causarano, Alan Franzluebbers, Joey Shaw, D. Wayne Reeves, Randy L. Raper, Wes Wood, and M. Lee Norfleet.

Quantifying the impact of long-term agricultural land use on soil organic C (SOC) is important to farmers and environmental policy makers, but data are critically lacking. We determined SOC and related pools under conventional-tillage cropping (5-40 years), conservation-tillage cropping (5-30 years), and pasture (10-60 years) from farms in the Southern Piedmont and Coastal Plain Major Land Resource Areas. Soil at depths of 0-5, 5-12.5, and 12.5-20 cm was collected from 72 fields in GA, SC, NC and VA and analyzed for total C, particulate organic C and microbial biomass C. The experimental design allowed us to separate the influences of land use from mean climatic conditions (i.e., temperature and precipitation) and physiographic region. Summed to a depth of 20 cm, SOC averaged 36.5 Mg C ha-1 in the Coastal Plain and 32.2 Mg C ha-1 in the Piedmont. Soil organic C averaged 41.9 Mg C ha-1 under pasture, 34.0 Mg C ha-1 under conservation tillage and 27.2 Mg C ha-1 under conventional tillage. The greatest statistical differences in SOC among land uses occurred at the 0-5 cm depth.  These data will be used to evaluate the potential of agricultural land use to store SOC and alter soil quality under different conditions in the southeastern USA.

 


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