Abstract:This study aimed to analyze the effects of rice straw (rice straw) and its different ingredients (decomposed rice straw, dissolved organic material, non-active ingredient rice straw) on microbial biomass carbon, nitrogen (MBC, MBN) and dissolved organic carbon, nitrogen content (DOC, DON) in the well-drained paddy soil from quaternary red clay. An indoor thermostatic incubation experiment was carried out. The results showed, compared to the control (S treatment), rice straw (RS+S treatment), decomposed rice straw (DRS+S treatment) and non-active ingredient rice straw treatment (NARS+S treatment) increased by 11.17% (p<0.01), 1.83% and 6.25% (p<0.05) in MBC, respectively, dissolved organic material treatment decreased by 2.67% in MBC. RS+S treatment increased by 15.29% in MBN, while DRS+S, DOM+S, and NARS+S decreased by 15.19%, 3.09% and 15.92% in MBN, respectively. Compared with S, RS+S, DRS+S, DOM+S and NARS+S treatments significantly increased by 13.33%, 10.88%, 6.81% and 11.41% in DOC, respectively (p<0.01); RS+S, DRS+S and DOM+S treatments significantly increased by 6.96%,10.84% and 10.12% in DON, respectively (p<0.05); and NARS+S treatment significantly increased by 13.41% in DON (p<0.01). Compared with S, DRS+S and NARS+S treatments significantly increased MBC/MBN (p<0.01), while RS+S treatment significantly decreased the MBC/MBN (p<0.05), and DOM+S treatment almost had no effect on MBC/MBN. Among the treatments, there were no significant differences in DOC/DON.As for MBC, MBN, DOC and DON in the well-drained paddy soil from quaternary red clay, rice straw and the different ingredients work in the same direction, but in different degree. The findings can provide a basic data for understanding the controls of rice straw and its different ingredients on MBC, MBN, DOC and DON, and a scientific basis for revealing the relationship between the source and conversion of available nutrient in paddy soil, which are useful for improving the use efficiency of Rice Straw and soil fertility.