Study on long-term experiment of crop rotation and fertilization in the loess plateau Ⅱ. Relationship between soil enzyme activities and soil fertility

The correlation between soil enzyme activities and other soil properties was studied. The results of correlation analysis showed that soil organic C was correlated very highly significantly with urease activity (r=0.9384**), alkaline phosphatase activity (r=0.7854**), and protease activity (r=0.9105**), and the interrelationship between catalase, invertase activities and organic C content varied with fertilization and cropping patterns. The amount of fungi was significantly correlated with urease and protease activities, and the yield of winter wheat was significantly correlated with urease, alkaline phosphatase and protease activities except catalase. In this paper, the relationship between soil enzyme activities and nutrient factors and the effects of soil enzyme activities on soil nutrient content were analyzed by Principal Components Analysis (PCA) and Path Analysis (PA). According to the results of PCA, urease, alkaline phosphatase, and protease activity could be a better index to evaluate soil fertility in dry land than catalase and invertase activity.