ABSTRACT
The rate of decline is influenced by tillage practices, crops grown, crop rotations, soil characteristics, management of crop residues, fertilizer or manure applications, and climate. Effects of various management practices on soil organic carbon (SOC) concentration have been evaluated in several long-term studies in the southern Great Plains. Long-term monthly mean precipitation and storm runoff values from stubble-mulch watersheds. SOC and nitrogen concentrations decline when native grasslands are converted to croplands. SOC loss is influenced by such factors as crops grown, crop rotations, crop residue management practices, climate, soil characteristics, fertilizer and manure applications, and tillage practices. In general, rates of OC loss increase as tillage intensities increase, are greater for cropping systems involving fallow than with continuous cropping, and are greater for row crops than for small grain crops. Although annual grain and forage yields have been greatest with continuous sorghum, SOC concentrations have been greater with continuous wheat and wheat-fallow cropping systems.
