Distribution and enrichment characteristics of organic carbon and total nitrogen in mollisols under long-term fertilization. Effect of various longterm fertilizations on soil nitrogen concentration anddistribution percentage in particlesize fractions Variation  of soil organic carbon under different vegetation types in Karst mountain areas of Guizhou Province, Southwest China. Responses of Fractal Feature of Soil Particle, Microbe and Enzyme Activity to De-farming Patterns of Slope Farmland in Southern Sichuan Province of China