Land use changes induced soil organic carbon variations in agricultural soils of Fuyang County, China

The purpose of this study is to understand spatial and temporal variations of soil organic carbon (SOC) under rapid urbanization and support soil and environmental management. SOC data in 1979 and 2006, of 228 and 1,104 soil samples respectively, were collected from surface agricultural lands in Fuyang County, East of China. Land use data were also gathered at the same time. The mean SOC was 17.3 (+/- 4.6) g/kg for the 1979 data and 18.5(+/- 5.8) g/kg for 2006. There was a significant difference in SOC between the 2 years according to the t test result. Geostatistical analysis indicated that SOC had a moderate spatial correlation controlled by extrinsic anthropogenic activities. The spatial distribution of SOC, derived from ordinary kriging, matched the distribution of industry and urbanization. Using a six-level SOC classification scheme (< 3.5, 3.5-5.8, 5.8-11.6, 11.6-17.4, 17.4-23.2, and > 23.2 g/kg) created by Zhejiang Province, approximately 15 % of soil had SOC increase from low to high levels from 1979 to 2006. The main cause of SOC variation in the study area was land use change from agriculture to industrial or urbanized uses. The increasing SOC trend near most towns may be attributed to use of organic manure, urban wastes, sewage sludge, and chemical fertilizers on agricultural land.