Soil organic carbon and total nitrogen as affected by land use types in karst and non-karst areas of northwest Guangxi, China

BACKGROUND: Human migration from the karst area to the non-karst area is an important approach for the restoration of degraded karst ecosystems. However, the effects of human-induced land-use change on soil properties are still unclear. The objective of this study was to investigate the effects of land use and parent material on soil organic carbon (SOC) and total nitrogen (TN) at a depth of 015 cm in karst and non-karst areas in southwest China. RESULTS: In the karst area, SOC and TN under different land uses decreased significantly in the order of secondary forestland>scrubland and abandoned farmland>farmland, commercial forestland and forage grassland. In the non-karst area, SOC and TN were the highest in scrubland and grassland, and were significantly higher than those in farmland and commercial forestland. Because of differences in parent material, SOC and TN were significantly higher in the karst area than those in the non-karst area. CONCLUSION: Abandoned farmland had the potential to increase SOC and TN significantly but land reclamation and cultivation had the opposite effect. SOC and TN were higher but cultivation-induced losses occurred more rapidly in calcareous soils than in red soils, indicating that more attention is needed for soil productivity and land use management in the karst area. (C) 2011 Society of Chemical Industry