[Effects of addition of organic carbon with different chemical structure on the fate and accumulation of exogenous carbon in red and sandy soils].

Plant litter input has important influences on soil CO emission and soil organic carbon (SOC) formation in terrestrial ecosystem. However, it is not well known for the fate of carbon when exogenous organic matters with different chemical structures are added to soil with different textures. In this study, we added the uniformly C-labelled substrates of glucose, starch, and cellulose to red soil and sandy soil, and compared the net C accumulation and recovery and its proportions in soil releasing CO, SOC, dissolved organic carbon (DOC) and microbial biomass carbon (MBC) pools. The results showed that δC values increased after exogenous substrate additions in CO, SOC, DOC, and MBC, and that the peaks of δC in CO pool appeared delay with increasing chemical structure complexity. The fate of exogenous C and its contributions of different C pools were significantly influenced by exogenous C types, soil types, and incubation times. In sandy soil, the added exogenous C was more mineralized as CO, with the net accumulation and recovery of C in CO pool decreasing in the order of glucose>starch>cellulose. In red soil, more exogenous C was transferred to SOC pool, with the net accumulation and recovery of C in SOC pool decreasing in the order of glucose>starch>cellulose. Our results implied that the chemical structure of exogenous substrates and soil texture together controlled the fate and accumulation of exogenous organic carbon.