Management effects on C accumulation and loss in soils of the southern Appalachian Piedmont of Georgia

Soil conservation management practices can impact on soil C storage. Long- and short-term data sets from three research sites were used to assess effects of management on C content of soils on the southern Appalachian Piedmont of Georgia. Intensive cultivation resulted in no observable change in total C content at the end of 3 yr, but at the end of 16 yr there were 40% and 18% declines in C in conventional tillage (CT) and no-tillage (NT) soils, respectively, at the Horseshoe Bend site. No significant changes in soil C were observed in either CT or NT soils at the end of 16 yr at Griffin. Higher clay content of Griffin soils may have contributed to this difference. Newly established NT plots on C-depleted soils on Dawson Field showed no change in C content at the end of 3 yr on both a highly eroded Pacolet sandy clay loam and a slightly eroded Cecil sandy loam. A soil under long-term NT accumulated C at a mean rate of ca. 0.6 Mg C ha^?1 yr^?1, reaching 29 Mg C ha^?1 after 20 yr. Steady-state levels of C in soils of the region may approach 40 Mg C ha^?1 (0–20 cm depth). Long-term forested and sod-based soils at Griffin showed C contents approximating this steady-state, while fertilized NT soils exceeded the estimated steady-state level.