Effect of straw on enzyme activity,inorganic nitrogen and CO_2 respiration of root zone soil

The field plot and the indoor soil incubation experiment were conducted to research the effect of straw on enzyme activity,total inorganic nitrogen and respiration of the root zone soil.Results showed that both of urease activity and invertase activity increased with straw increasing.There was a significant difference between catalase activity and amount of straw,but catalase activity gradually reduced with incubation time.Polyphenol oxidase activities had different change patterns with that of the other enzyme activities;Activities of polyphenol oxidase of soybean field soil were higher than that of corn field.The content of soil inorganic nitrogen increased with incubation time.There was no significance among treatments of straw applied to soybean field soil,but it was significantly different between treatments of corn field soil.The respirations among all the treatments were significantly different with each other,and the respirations of corn field soil were higher than that of soybean field soil.The correlation analysis showed that all the four enzyme activities of corn field soil had significant correlation with inorganic nitrogen and respirations,and the activities of urease and polyphenol oxidase of soybean field had a very significant correlation with soil inorganic nitrogen.Therefore,the addition of straw could improve soil microbial activity,and promote soil enzyme activities and soil inorganic nitrogen content.