Soil change after three decades of conventional till, no-till, and forest succession in the Piedmont of Georgia, USA

In the Piedmont of Georgia, a long-term experiment between conventional (CT) and no-till (NT) agriculture has provided insight into the effects of tillage on biogeochemical cycles and soil structure. In this study, adjacent land undergoing forest succession (FS) was added to the agricultural comparison to assess effects on soil organic carbon (SOC), acidification, and aggregation. Three decades of NT and FS have led to similar contents of SOC that exceeds the content under the CT profile (0-2 m) by 20%. Accumulation of carbon in forest biomass relative to CT or NT vastly exceeds SOC differences. Forest uptake of exchangeable soil cations and agroecosystem fertilization explain a deep soil acidification that has occurred under FS. Compared to CT, aggregate stability has improved to a depth of 5 cm under NT and to 28 cm under FS. Forest soil processes can produce water-stable aggregates within a year that may be linked to SOC stabilization.