The rate of soil carbon storage no-till farmland is uncertain due to environmental and production factors. The objective of this research is to compare changes in total soil organic carbon (SOC) among different cropping systems in two regions of
Tennessee under no-tillage production. The experiment used a split-block treatment design with four replications at each location. The whole-block treatment was cropping sequences of Roundup Ready® corn (
Zea mays), soybeans (
Glycine max), and cotton (
Gossypium hirsutum) combined with a split-block treatment of bio-covers using winter wheat (
Triticum aestivum), hairy vetch (
Vicia villosa), poultry litter, and winter weeds. Treatments were applied to fields at the
University of
Tennessee’s Research and
Education
Center’s at Milan (RECM) and Spring Hill (MTREC). Soil samples were taken before treatments began and after two and four years of experimentation. SOC was measured at the surface (0-5 cm) and subsurface (5-15 cm). Changes in SOC were calculated. Overall, both locations showed small but consistent loss in carbon over all treatments during the first two years, being largest in the surface layer, at the RECM site. Mean SOC loss at RECM surface was 1.47 Mg ha
-1 while that of MTREC was 1.28 Mg ha
-1. The subsurface showed a similar trend, with mean SOC loss at RECM being higher (0.65 Mg ha
-1) than at MTREC (0.55 Mg ha
-1). A significant effect (P<0.001) was seen in the surface of the RECM site due to biocover. Poultry litter (0.9 Mg ha
-1) and wheat (1.27 Mg ha-1) resulted in less SOC loss than hairy vetch (1.87 Mg ha
-1) and winter weeds (1.88 Mg ha
-1). Although non-significant, similar trends were seen in plots under the biocover treatments in the subsurface at both the RECM and MTREC sites. Results will be presented on SOC levels after four years of the cropping systems.