Effects Of Rice Straw Returning On Soil Enzyme Activities And Soil Nutrients

Straw returning could impove soil nutrients, enhance soil enzume and reduce the soil pollution and degradation which caused by excessive use of chemical fertility. The experiment focused on the cold rice, which used plot experiment and laboratory simulation experiment, and studied the effects of rice straw returning on soil enzyme activities and soil nutrients so as to provide evidence and reference for the rice straw returning.The results showed that:The activities of acid phosphatase with straw returning were higher than that of no straw returning, which increased with the amount of straw returned.In adition to the activities of acid phosphatase with no straw returning decreased gradually in laboratory simulation experiment, the activities of acid phosphatase were increased firstly and then decreased. The neutral phosphatase activities were relatively stable in the plot experiment. In the laboratory simulation experiment, the neutral phosphatase activities decreased sharply after 10 days then rose finally stabilized. The activities of neutral phosphatase with straw returning were higher than that of no straw returning. The activities of alkaline phosphatase first increased and then decreased with the rise in the final in the plot experiment, which first increased and then decreased in the laboratory simulation experiment. The activities of alkaline phosphatase with straw returning were higher than that of no straw returning, which increased firstly and then decreased with the amount of straw returned, the alkaline phosphatase activities of 0.5STR reached its peak in the plot experiment, the alkaline phosphatase activities of 1.0STR reached its peak in the plot experiment.The activities of urease presented decreased-increased- decreased in the plot experiment. The activities of urease with straw returning were lower than that of no straw returning. The activities of urease decreased gradually in the aboratory simulation experiment, which decreased firstly and then increased with the amount of straw returned, for 2.0STR>1.5STR>STM>0.5STR >1.0STR. The activities of invertase enzyme first increased and then decreased, the activities of invertase enzyme with straw returning were higher than that of no straw returning, the invertase enzyme activities of 1.0STR reached its peak.The content of total nitrogen, total phosphorus, total potrssium,NH4+-N, NO3--N, available phosphorus and available potrssium were increased by straw returning. The content of inorganic nitrogen, NH4+-N, NO3--N decreased gradually. The content of inorganic nitrogen decreased firstly and then increased with the amount of straw returned, for 2.0STR>1.5STR>STM>0.5STR >1.0STR. The content of NH4+-N increased with the amount of straw returned. The content of NO3--N decreased with the amount of straw returned. The content of available phosphorus and available potrssium first increased and then decreased. The content of available phosphorus and available with straw returning were higher than that of no straw returning.There was a correlation between the soil enzyme activities and soil nutrients, there were a positive correlation between the acid phosphatase activities and the content of available P, available K. There were a positive correlation between the invertase enzyme activities and the content of available P, available K, inorganic nitrogen, NH4+-N, NO3--N. There were a positive correlation between the urease activities and the content of inorganic nitrogen, NH4+-N, NO3--N. The rice yield with straw returning were higher than that of no straw returning, the rice yield of 0.5STR were higher than the rice yield of 1.0STR.Tlllering and effective tlllering were increased by straw returning.