Characteristics of surface soil erosion of karst valley in different land use types at Nanping in Chongqing

The research on the characteristics of soil erosion in karst regions was carried out in order to prevent soil erosion better and prevent from rocky desertification. The characteristics of surface soil erosion in karst areas were obtained through nine runoff plots monitoring from January, 2008 to August, 2010. The conclusions were as follows: the enrichment of soil nutrients displayed differently: available K was the highest, total phosphorus was the lowest, and total nitrogen, hydrolysable nitrogen and organic matter were between them. Enrichment levels of soil nutrients in different land use types were different: Sloping land was the most significant (natural slope farmland had stronger enrichment than that of farmland moving soil to build up fertility), followed by woodland, honeysuckle, and grass land. The correlation between the nutrient content and the rain intensity was significant and the correlation between the nutrient outflow and the rain flow was positive but weak. The total loss of soil nutrients was closely related to rainfall and its intensity as well. The modulus of soil erosion reflected differently in different land use types: the slope farming>the honey suckles>the lawn>the forest land. Runoff in karst regions took place only when big rain especially rainstorm occurred, which runoff coefficient was about 2.31%-14.72%. The characteristics of soil erosion can provide scientific basis for preventing soil erosion.