Spatial distribution and estimating of soil organic carbon on Jingyu County, Jilin province

Soil organic carbon (SOC) loss is a big source of CO₂ emission to the atmosphere, but we have insufficient understanding of the loss process. Understanding the history of SOC stock is thus necessary in attempts to reduce carbon emissions from SOC. Black soil is a big SOC sink in China, but there has been little scientific research conducted on this issue. Based on soil type data from the Second National Soil Survey and county soil type maps, soil organic carbon density (SCOD) and stocks of topsoil in Jingyu County, Jilin Province were calculated. Our results show that SOCD in 0-15cm depth varied from 0.61-36.80 kg·m^-2 and in top 1m varied from 11.81-133.07kg·m^-2, and had a mean value of 6.14kg·m^-2 and 28.63kg·m^-2, total 18430Bg (1Bg=10⁹g) and 85915Bg, respectively. A linear regression analysis between SOCD and total nitrogen (TN) content in different depths performed show a good correlation, TN=0.2082+0.4491×SOCD (R=0.9676, PO.0001), (0-15cm) and TN=-0.00941 +0.073 × SOCD (R=0.955, P<;0.0001), (0-1m). We also calculated the SOCD using the equation and the record of TN in Jingyu County soil species in two depths. Kriging interpolation algorithm was used to analyze the soil organic carbon density by Arc GIS 9.2, and the results show that human activities lead to a reduction in SOCD in soil, as indicated by our study of Jingyu County. In addition, this research can also provide a reference for future assessment.