Soil organic carbon under different landscape attributes in croplands of Northeast China

Soil organic carbon (SOC) was measured in topsoil samples of agricultural soils from 311 locations of Jiutai County, Northeast China. The spatial characteristics of SOC were studied using the Geographic Information Systems and geostatistics. Effects of other soil physical and chemical properties, elevation, slope, soil type and land use type were explored. SOC concentrations followed a lognormal distribution, with a geometric mean of 1.50%. The experimental variogram of SOC has been fitted with an exponential model. Our results highlighted total nitrogen and pH as the soil properties that have the greatest influence on SOC levels. Upland eroding areas have significantly less SOC than soils in deposition areas. Results showed that, soil type had a significant relationship with SOC, reflecting the effect of soil parent materials. Soil samples from paddy fields and vegetable fields had higher SOC concentrations than those from dry farming land.