Effects of Single and Multiple N Application under Different Total N Fertilizer on the Amount of Microorganisms and Activity of Enzymes of Soybean

In this paper,a pot experiment was conducted to study the effects of single and multiple N application under total N fertilizer on the quantity of microorganisms,biodiversity indices,activity of enzymes and yield of planted soybean.The results showed that bacteria were the predominant microorganisms,and the total number of soil microorganism varied with the dynamic changing of the amount of soil bacteria.Whether the single or the multiple N application,the change of bacteria and total microorganisms showed a decreased trend with the increasing nitrogen application rate.Under the same N application rate,the treatments with the multiple N application had more microorganisms than that of the treatments with the single N application,increased by 30.3% and 6.3%,respectively,except the treatment with 225 kgN/hm2.However,the biodiversity indices showed the opposite trend.The treatments with single N application showed first increased and decreased thereafter with the increasement of nitrogen application rate.In addition,the trend of those of the treatments with multiple N application showed increased with the increasement of nitrogen application rate.Moreover the treatments with single N application had higher urease and invertase enzyme activity than that of multiple N applications.