中文摘要：

土壤酶作为土壤生态系统的主要组成部分之一,在营养物质转化、肥力水平提高、污染物清除等方面发挥着重要作用。本文采用长期定位试验地土样,测定了三大水解酶活性,并构建了土壤酶总体活性指标。结果显示：土壤酶活性可明显反映培肥效果的优劣;土壤化学性质与酶活性间呈显著或极显著正相关,揭示出土壤脲酶、转化酶和碱性磷酸酶在一定程度上均可表征土壤肥力水平;构建的土壤总体酶活性指标（Et=sum Xi/X,from i=1 to n Total enzyme activity index）的优点是消除了不同土样酶活性的量纲及大小的影响,且无量纲的最终参数便于比较;计算获得的土壤总体酶活性参数,可更好表征土壤中总体酶活性和肥力水平高低,结果与主成分、聚类分析的相同。

英文摘要：

As one of the major components in soil ecosystem,soil enzyme plays important roles in converting soil nutrient,improving soil fertility and remediating pollutant in soil.This study focused on long term monitoring enzyme activities of three hydrolytic enzyme（urease,invertase,alkaline phosphatase） from fixed sites at fertile land to establish a more realistic index of total soil enzyme activity.The result showed that there is a good correlation between soil enzyme activity and soil fertility.Correlations between soil enzyme activities and characteristics of the soil are significantly or very significantly positive.This suggests that enzyme activities of urease,invertase and alkaline phosphatase in soil environment could be used as an indicator for soil fertility.A new total soil enzyme activity index from this study（Et=∑ni=1Xi/X） was proposed which is a dimensionless parameter and could be used to compare with each soil samples easily.The Et can be calculated from monitoring enzyme activity in soil and soil fertility,as the result of total soil enzyme is similar to those of principal component analysis（PCA） and clustering analysis.