Soil erosion affects the soil environment and exerts an important impact on the soil organic carbon distribution, deposition, conversion, and carbon dioxide emission. The soil microbial biomass carbon can respond sensitively to these changes. The soil microbial biomass carbon under erosion and sedimentation conditions was studied for the erosional slopes at five organic carbon levels at typical erosion and deposition sites in the hilly loess plateau region. Through the study of the soil microbial biomass carbon in the rainy season, the influencing factors and their degree of influence on the soil microbial biomass carbon of the slope soil under erosion-sedimentation conditions were analyzed. The results showed that ① Soil erosion lead to significant spatial and temporal differentiation in the soil temperature and humidity and the soil organic carbon in the erosion and sedimentary area on the slope, and the degree of differentiation was related to the soil organic carbon level. ② The soil microbial biomass carbon increased significantly at the end of the rainy season, with an increase of 91.08%-286.83%. The soil microbial biomass carbon content in the slope sedimentary area was higher than that of the erosion area. With increasing soil organic carbon level, the difference between the soil microbial biomass carbon content of the erosion and sedimentary area increased, and its spatial differentiation increased. ③ The soil microbial biomass carbon in the erosion and deposition areas responded differently to the soil organic carbon content, temperature, soil moisture, and other factors. Before the rainy season, the soil microbial biomass carbon was most sensitive to soil moisture changes. However, at the end of the rainy season, the soil microbial biomass carbon was most sensitive to soil temperature changes in the deposition zone. The soil microbial biomass carbon was most sensitive to the soil organic carbon in the erosion zone. Soil erosion and seasonal variation were important reasons for the spatial and temporal distribution of the soil microbial biomass carbon on the eroding slopes. The differences in the sensitivity of the soil microbial biomass carbon to the different influencing factors was mainly due to the restrictive conversion of the different factors.
