Soil Quality Evaluation and Obstacle Factors of Erosion Slop in Karst Trough Valley Area

[Objective] In order to accurately evaluate the soil quality characteristics of the dip/anti-dip erosion slope in the karst trough valley screen out suitable soil quality evaluation methods and explore the obstacle factors limiting soil quality in this area. [Methods] Five typical land use types (forest land, grassland, bare land, corn land, pepper land) were selected as the research objects in Qingmuguan Karst trough Valley of Chongqing, and the minimum data set (MDS) was established by principal component analysis combined with Norm value. The nonlinear soil quality evaluation method and membership function were used to evaluate the soil quality of the diplanti-dip erosion Slope and down-slope in the karst trough valley. [Results] (1) MDS of soil quality evaluation indexes in karst troughs valleys included capillary water capacity, capillary porosity and total phosphorus. (2) According to the nonlinear soil quality evaluation method, the soil quality of anti-dip erosion slope (0.519) was better than that of dip erosion slope (0.451). The soil quality of anti-dip erosion slope forest land was the best (0.653), and that of pepper field was the worst (0.426). (3) The coefficient of determination (R2) of the nonlinear evaluation method was higher than the membership function in the dip erosion slope and the anti-dip erosion slope, so the non-linear scoring model was more suitable for the karst trough valley. (4) There were significant differences in soil quality barrier factors, and only total nitrogen was the common barrier factor. [Conclusion] Appropriately increasing grassland and forest cover can improve soil quality in karst trough and valley area. The results of this study can provide basis for soil quality control and rational fertilization of slope erosion along/against slope in karst trough valley according to local conditions.