Submitted to: Soil & Tillage Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/28/1998
Publication Date: N/A
Interpretive Summary: Soils from research sites near Athens, Griffin, and Watkinsville, Georgia were sampled to assess the effects of management on soil carbon storage. At the end of 16 years of double-cropping following pasture near Athens, soil carbon declined by 40% using conventional tillage and 18% using no tillage. Under similar management at Griffin, no significant changes in soil carbon were observed with either conventional or no tillage at the end of 16 years. Newly established NT plots on C-depleted soils near Watkinsville resulted in a 14% increase in C content at the end of three years on a highly eroded Pacolet sandy clay loam, but no change was observed in a slightly eroded Cecil sandy loam. Soil carbon in a small watershed managed with no tillage and double-cropping accumulated at a rate of approximately 0.6 Mg/ha/year during 20 years. Steady-state levels of soil carbon of the Southern Piedmont region may approach 40 Mg/ha to a depth of 20 cm. High biomass production using double-cropping and minimal soil disturbance, whether under crop, forage, or tree culture were essential to maintaining high levels of carbon in these soils in a climate that favors rapid decomposition.
Technical Abstract: 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. Intensive cultivation resulted in no observable change in C content after three years, but after 16 years there were 40% and 18% declines in C in conventional (CT) and no tillage (NT) soils, respectively, at the Horseshoe Bend site. No significant changes were observed in either CT or NT soils after 16 years 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 a 14% increase in C content after three years on a highly eroded Pacolet sandy clay loam, but no change was observed in a slightly eroded Cecil sandy loam. Again, clay content appears to play a role. A long-term NT soil showed a C accumulation rate of ca. 0.6 Mg C/ha/year, reaching 29 Mg C/ha after 20 years. Steady-state levels of C in soils of the region may approach 40 Mg C/ha (0-20 cm depth). Long-term forested and sod-based soils at Griffin showed C contents approximating steady-state, while fertilized NT soils exceeded the predicted steady-state value.