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.