Responses of Soil Organic Carbon Fractions to Land Use Types in Hilly Red Soil Regions, China

Land use type exerts important influences on soil organic carbon (SOC) and its fractions, and determines the stability of the carbon pool. Taking woodland as a reference, the content of SOC and its labile fractions [dissolved organic carbon (DOC), microbial biomass carbon (MBC), and particulate organic carbon (POC)] and non-labile fractions [mineral-associated organic carbon (MAOC)] in upland and paddy surface soils in hilly red soil regions were determined to explore the responses of SOC fractions to land use type. The results showed that the contents of SOC, MBC, POC, and MAOC ranked highest in paddy compared with upland and woodland. DOC content in woodland was significantly higher than in upland and paddy (Pwoodland>upland. MAOC content ranked the highest in paddy but the lowest in upland, while MAOC/SOC exhibited the opposite trend. The correlation suggested that the labile fractions (MBC and POC) and inert fraction (MAOC) were significantly positively correlated with SOC (P0.05). There was a significant positive correlation between POC and MBC in upland and woodland (P © 2020, Science Press. All right reserved.