Study On Soil Anti-erodibility And Anti-scourability Under Different Land Use

Soil erosion is an biggest world environment problem, the most potential dangers of Chinese ecological security, the main ecological environmental problems of Yangtze river basin and one of the four water problems.Aiming at the need of construction of upper Yangtze river ecological problems and the important contents of soil erosion research, the characterisitics and influence factors of soil anti-erodibility and anti-scourability were studied by the methods of field investigation, laboratory analysis and simulation test. At the same time, soil erosion essence was revealed in this paper. The main results were as follows.1. Biological indicators can be mergeded into the evaluation of soil anti-erodibility, such as urease, acid phosphatase. All the 23 anti-erodibility indices could be optimized to be 8 indices which were<0.001mm clay, structural particles index, water stable index, soil erosion resistance index, dispersion coefficient, situation of aggregation, microbial biomass carbon and catalase by principal component analysis. The order of Principal component analysis(PCA) comprehensive exponent of soil anti-erodibility about these five land use types abovementioned displayed that Chinese fir plantation> Eucalyptus plantation>Loquat orchard> Tea plantation> Abandoned land.2. Soil internal physical and chemical properties had most effect on soil anti-erodibility, but the biological factor such as the characteristic of root had little effect on it. The correlation between soil mechanical composition, micro-aggregate composition and anti-erodibility was remarkable, and the remarkable correlation coefficient lied between 0.401～0.942. Aggregate in all diameters enhanced soil anti-erodibility by influencing water stable index, soil erosion resistance index and catalase. The remarkable correlation coefficients between them lied between 0.425-0.872. Soil organical matter and CEC had remarkable correlation with soil anti-erodibility.3. The sediment concentration of all land use types was high at the beginning, then decreased gradually along with the scouring time after 3 to 6 minutes. Soil anti-scourability assumed wavy variation along with scouring time. And it also accorded with the law that anti-scourability increased gradually with scouring time. The change regulation of the index of soil anti-scourability along with scouring time obeyed the power function. The fitting effect was good and its correlation index lied between 0.717～0.989.4. Soil bulk density, porosity, micro-aggragate composition,>5 and 2～1mm aggregate and<1mm fibrous root were the main factors of soil anti-scourability under different land use types. The index of soil anti-scourability was significantly negative correlation to soil bulk density and significantly positive correlation to soil porosity, and the respective correlation coefficient was-0.943,0.946.0.01～0.001mm,<0.001mm and 0.05～0.01mm contents of micro-aggregate composition were significantly correlation to the index of soil anti-scourability, and the respective correlation coefficient were 0.744, 0.997,-0.449. Root length, surface area and volume of