Total and Active Soil Organic Carbon from Long-term Agricultural Management Practices in West Tennessee

Soil organic carbon (SOC) content is strongly influenced by agricultural management practices. Leveraging three long-term field experiments in Tennessee, this study analyzed the effect of crop rotation, tillage, and cover crops on SOC and permanganate-oxidizable C (POXC) at various soil depth increments (0-2.5, 2.5-5, 5-7.5, 7.5-10, 10-15, 15-22.5, 22.5-30, 30-45, and 45-60 cm), as well as at the 0-to 15-cm profile. Corn (Zea mays L.) and cotton (Gossypium hirsutum L.)-based systems showed increased SOC from 0 to 22.5 cm compared with soybean [Glycine max (L.), Merr.]-based systems. Additionally, no-till systems accumulated more SOC than tilled systems from 0 to 5 cm, but cover cropping showed no effects. Results also showed a significant positive relationship between SOC and POXC (P < 0.0001, r(2) = 0.93). This study revealed that SOC and POXC are strongly influenced by management practices in the surface shallower depth increments of southeastern US croplands.