Characteristics Of Soil Organic Cardon In The Rocky Desertification Region, The Central Area Of Hunan Province

In recent years, the development of rock desertification accelerates the deterioration of environment in the central area of Hunan Province. The rock desertification in this area make soil erosion more serious, natural disaster more frequent and ecosystem degenerate. People that living there are facing an unprecedented crisis. By study on variation of soil organic carbon in the rocky desertification evolution, we can find some theoretical basis for controlling the rock desertification and recovering environment.This research collected soil samples in different levels of rock desertification in central area of Hunan Province and Determined the soil physical and chemical properties by indoor tests. Then using some software to count data, and finally make a lot of comparisons on variation of soil organic carbon in different rock stage and have their correlation with the soil physical and chemical properties. Through many analysis, we can preliminarily conclude that:(1)Along with the degree of rocky desertification, soil organic carbon content of rocky desertification grades showed a trend of declining. Mild, moderate, severe rocky desertification area of the soil organic carbon content less than evergreen in the control group, and there were significant differences (p<0.05). Between rocky desertification grades, by evergreen in the control group evolve into rocky desertification, soil organic carbon content is very significant; And with further serious rocky desertification happening, soil organic carbon had no significant change.(2) In rocky desertification evolution process, soil erosion, soil physical properties changed. First soil bulk density increase, sand proportion to drop, soil powder sand and clay content increase, the nature of soil water content did not change significantly. Rocky desertification cause destroy soil structure, soil strength increased, structure degradation, retention of fat and fully ability decline. At the same time, the larger changes in the chemical properties of soil have happened. Rocky desertification area of soil total nitrogen, total phosphorus, soil available phosphorus and soil available potassium content compared with the control group, has a larger degree of decline.The vertical variations of soil properties with soil depth in the sample plots, soil physical properties, besides the natural water content, soil capillary moisture capacity, soil grains of sand, coarse powder proportion are falling. In soil chemical properties of total nitrogen, total phosphorus, effective phosphorus, available potassium decrease with the increase of soil depth, total potassium content had no significant change.(3) Using the SPSS17.0Pearson method, total nitrogen, total phosphorus and soil microbial carbon have very significant relationship with soil organic carbon. As the same time, soil bulk density, coarse sand have very significant relationship with soil organic carbon. Soil properties like the soil potassium, effective potassium and effective phosphorus correlation is not high. Stepwise multiple regression analysis can be concluded that, in karst rocky desertification area of soil organic carbon content influence the highest factor for the total nitrogen content, standardized coefficient up to1.134, and the total phosphorus the second highest factor. Silt is the third factor affect soil organic carbon content.This thesis preliminarily probes the variation properties of soil organic carbon and the nature of soils changes in different rock stage. It provides an important reference for further study on the changes of soil natures in rocky desertification.