Effect of Rock Strata Dip on Soil Detachment Capacity of Different Land Use Types in Karst Trough Valley Area

[Objective] This study aimed to explore the influence mechanism of rock strata dip on soil erodibility and provide references for preventing and controlling water and soil erosion in karst trough valley area. [Methods] The study focused on the dip/anti-dip slope of Qingmuguan karst trough valley area in Chongqing city. Through flume erosion experiments, we analyzed the differences in soil erodibility between different land use types on the dip/anti-dip slopes and investigated the impact of soil physicochemical properties on soil erodibility. [Results] (1) Both dip/anti-dip slopes showed a significant negative correlation with organic matter content, >0.25 mm water-stable aggregates content, and total nitrogen content (p<0.05). In particular, the anti-dip slope had higher organic matter content, >0.25 mm water-stable aggregate content, and total nitrogen compared to the dip slope. (2) Soil erodibility was higher on the dip slope than on the anti-dip slope for all four land use types studied. Additionally, grassland had lower comprehensive scores of soil erodibility than pepper fields, cornfields, and bare land on both the dip/anti-dip slopes. (3) Based on stepwise multiple regression analysis results, prediction models for soil erodibility on the dip/anti-dip slopes were established using organic matter content and >0.25 mm water-stable aggregate content as predictors with determination coefficients R2 of 0.77 and 0.85 respectively. [Conclusion] In summary, grassland had the lowest soil erodibility among all land use types studied regardless of the dip/anti-dip slopes in karst trough valley. Therefore, in order to prevent soil erosion and promote ecological restoration in karst trough valley, it is necessary to cultivate the land reasonably and increase grassland coverage appropriately, thus enhancing the soil's resistance against erosion.