Conservation tillage, rotations, and cover crop affecting soil quality in the Tennessee valley: Particulate organic matter, organic matter, and microbial biomass

The impact of conservation tillage, crop rotation, and cover cropping on soil-quality indicators was evaluated in a long-term experiment for cotton. Compared to conventional-tillage cotton, other treatments had 3.4 to 7.7 Mg ha(-1) more carbon (C) over all soil depths. The particulate organic matter C (POMc) accounts for 29 to 48 and 16 to 22% of soil organic C (SOC) for the 0- to 3- and 3- to 6-cm depths, respectively. Tillage had a strongth influence on POMc within the 0- to 3-cm depth, but cropping intensity and cover crop did not affect POW A large stratification for microbial biomass was observed varing from 221 to 434 and 63 to 110 mg kg(-1) within depth of 0-3 and 12-24 cm respectively. The microbial biomass is a more sensitive indicator (compared to SOC) of management impacts, showing clear effect of tillage, rotation, and cropping intensity. The no-tillage cotton double-cropped wheat/soybean system that combined high cropping intensity and crop rotation provided the best soil quality.