Spatial distribution of soil organic carbon and analysis of related factors in croplands of the black soil region, Northeast China

Little is known concerning the spatial variability of soil organic carbon (SOC) and the relationship between SOC and landscape aspects, in the black soil region of Northeast China, at county level. For this reason, the spatial characteristics of soil organic carbon and related factors, i.e. land use, topography, and soil type, etc., were explored using GIS and geostatistics, taking Dehui County, Northeast China, as a study area. Soil organic carbon in topsoil samples were taken at 354 locations in croplands of Dehui County. SOC concentrations follow a log-normal distribution, with an arithmetic mean of 1.61% and geometric mean of 1.55%. The experimental variogram of SOC has been fitted with an exponential model. Lower SOC concentrations were associated with larger gradient. Chernozems have the highest SOC concentrations, and those under aeolian soils have the lowest SOC values. The spatial distribution pattern of SOC concentrations interpolated by Kriging, indicated that after being divided into two parts along the Yinma River, samples in the western part have statistically higher SOC contents than those in the eastern part. This pattern is approximately consistent with the spatial structure of topography and land use type.