The Reserve Distribution Characteristics of Organic Carbon in Soil from Poyang Lake and the Surrounding Economic Region

Soil is a main component of the terrestrial ecosystem, and soil carbon research is significant in the carbon cycle and global change. Using the geochemical survey data from Poyang Lake in Jiangxi province and the surrounding economic zone multi-target regional, the total carbon and organic carbon from the surface, middle and deep soil in research area was studied and the organic carbon reserves and organic carbon density distribution characteristics analyzed. The results indicate that the overall carbon in the study area consists mainly of organic carbon. The reserve of organic carbon is 138 million tons and organic carbon density is 3512 t/km² in the surface soil (0-0.2 m), 439 million tons and 11156 t/km² in the middle soil (0-1.0 m) and 614 hundred million tons and 15617 t/km² in the deep soil (0-1.8 m). Compared with the national agricultural geological survey data, organic carbon density of surface soil in the study area is 10.86% higher than that of the national agricultural geology survey, however, organic carbon density of middle and deep soil is close to the results of national agricultural geology. It shows that the research area has huge reserves of organic carbon. Further studies were conducted to uncover the distribution and the distribution characteristics of organic carbon in soil by using the organic carbon density and organic carbon reserves for different soil types, different land utilization types, different geomorphic units and different administrative units. Research results suggest that each layers of soil possesses the same organic carbon density spatial distribution characteristics, which is closely related to the geological background and the vegetation coverage. A high value area of carbon density is located in hilly areas and mountainous regions, such as the paleozoic carbonaceous rock and coal strata from the north of Fengcheng City, the south of Gaoan City and the surrounding of Leping City. The highest organic carbon density occurred in the topsoil of Leping city. Low organic carbon density is located in lake and river valley areas. The results of this study provide reliable data for studying the carbon cycle and carbon emissions in the Jiangxi countryside.