Effect of long-term fertilization on soil enzymatic activities

The soil enzymatic activities and nutrient content were assayed in longterm fertilizing field. The results showed that under the condition of crop cultivation and fertilization, the main nutrient contents were increased, and the urease and alkaline phosphatase activities varied remarkably, while the polyphenol oxidase varied unremarkably. The correlation analysis of soil enzyme activity showed there was a positive correlation between soil urease and alkaline phosphatase, and there was also a positive correlation between these two enzymes and the main fertility factors. It was concluded that the soil urease and alkaline phosphatase activities could be used as comprehensive indices of fertility.