Soil Carbon Level Dependence upon Crop Culture Variables in a Thermic-Udic Region
This chapter aims to use about a decade of research that has been carried out near Watkinsville, GA as a data base from which to discuss soil carbon. During the 1970 to 1980 decade, large areas were devoted to continuous soybean production without a winter crop. Preplant tillage consisted of disc harrowing at least twice. Although some terrace systems were maintained which afforded some soil erosion control, many were only remnants and considered to be obstacles to freedom in cultivation. The quantity of water-stable soil aggregates was unchanged for the conventionally tilled grain sorghum and soybean that were rainfall dependent and planted into winter fallow. Soil carbon levels approaching that under forest have been achieved in 4 years with appropriate crop culture. The use of a no-tillage culture permitted the residue of both crops to serve as a mulch during decomposition and allowed soil carbon to accumulate in the surface 30 or 50 mm.