Effects of Different Amount of Wheat Straw Returning on Rice Growth,Soil Microbial Biomass and Enzyme Activity

The effects of different amount of wheat straw returning on yield of rice,microbial biomass-C,N and soil enzyme activity were studied through a in-situ experiment.The results showed that straw returning increased the number of tillers,plant height,the relative content of chlorophyll and aboveground dry matter,but the effect degree of different amounts were different;compared to the control,50% straw returning treatment significantly increased yield of rice(P0.05)with the increase of 10.2% in the theoretical yield and 9.0% in actual yield,respectively;Straw returning significantly improved soil total nitrogen and available nitrogen,and also had no obvious influence on soil organic matter,available phosphorus and available potassium;50% straw returning treatments enhanced microbial biomass-C,N(P0.05),and its microbial biomass-C,N were 1.5 times and 1.9 times higher than those from the control;25% and 50% straw returning treatments increased urease activity significantly(P0.05);25%,50% and 75% straw returning treatments promoted catalase activity with the increase of 9.28%,12.11% and 8.51%(P0.05);50% straw returning treatment significantly increased invertase activity by 20.30% in comparison to the control(P0.05).Due to long-term effects on yield of rice and soil fertility of straw returning and the complexity of effects of straw returning on microbial physiological metabolism,long-term in-situ study need to be carried out to better understand the reasonable amount of straw returning.