Land use affects soil organic carbon fractions in karst areas. Different types of land use impact soil properties differently. Soil microbial biomass carbon and Cmic-to-Corg ratios vary between vegetable, orange, slopping field, grassland, and shrub land. Soil K2SO4-soluble carbon is a good indicator of soil fertility changes. Soil composition, like sand content, also influences soil organic carbon fractions. Overall, land use plays a significant role in determining soil quality and carbon distribution in karst regions.