中文摘要：

采用主成分分析法研究了太湖地区水稻土25a长期定位试验稻麦两季的土壤酶活性与土壤肥力之间的相互关系。结果表明，稻麦两季的脲酶、酸性磷酸酶、碱性磷酸酶、β-葡糖苷酶和芳基硫酸酯酶活性与肥力因子大都具有不同程度的显著线性相关关系。特别是酸性磷酸酶和β-葡糖苷酶，其稻麦两季的酶活性与pH、速效氮、速效磷和有机质之间均呈显著或极显著线性相关。结合土壤酶活性及肥力因子对稻麦两季14种处理进行分析，筛选出影响土壤肥力的主要因子群并进行了综合评价：土壤酶活性可作为反映土壤肥力的重要指标，且磷酸酶、芳基硫酸酯酶和β-葡糖苷酶活性作为综合评价指标优于脲酶。氮磷肥配施是最优的培肥模式；在施用其他肥料的基础上增施磷肥能够提高土壤肥力；不施肥或仅施有机肥均会导致土壤肥力的退化；秸秆还田可提高麦季土壤肥力水平，而对稻季的无明显影响。

英文摘要：

Principal component analysis was used to study relationship between soil enzyme activity and soil fertility of paddy fields under the wheat-rice cropping system in a 25-year long-term experiment in the Taihu region. Results show that significant linear relationship was observed of soil fertility factors with the activities of urease, acid phosphatase, alka- line phospatase, β-glucosidase, and arylsulfatase, especially acid phosphatase and β-glucosidase, which showed significant or extremely significant linear relations with pH, available N, available P and organic matter. Analysis was carried out of the 14 treatments of the experiment and soil enzyme activities and fertility factors therein, and main factor groups affecting soil fertility were screened out for comprehensive evaluation. The evaluation reveals that soil enzyme activities may be cited as important indexes reflecting soil fertility, and phosphatase, arylsulfatase and β-glucosidase are better than urease in this function. Combined application of N and P fertilizers is the optimal soil building mode. Addition of phosphate fertilizer in fertilization can increase soil fertility. No fertilization or application of organic manure only will lead to degradation of soil fertility. Straw incorporation can improve soil fertility in the wheat season, but has no obvious effect in the rice season.