Spatial heterogeneity of soil microbial biomass carbon, nitrogen, and phosphorus in sloping field in a groge Karst region, Southwest China Effects of different planting modes on the soil permeability of sloping farmlands in purple soil area. Spatial heterogeneity of soil microbial biomass carbon, nitrogen, and phosphorus in sloping farmland in a karst region on the Yunnan-Guizhou Plateau