中文摘要：

对长江三角洲地区近20年来土壤质量演变趋势分析得出：研究区土壤肥力质量总体呈上升趋势。土壤有机质含量先降后升；全N、速效N含量分别呈S型、直线上升趋势，局部地区有积累趋势；速效K和土壤pH值下降明显；土壤盐基交换量（CEC）有增高趋势。土壤环境负荷呈增大趋势，表现为土壤氮、磷出现季节性盈余，对水体富营养化贡献率大；土壤重金属有明显积累特征；土壤有机磷、有机氯等农药、除草剂、表面活性剂在生态链中仍有一定影响。

英文摘要：

By analysis over the past 20 years, the conclusion was obtained that the general trend in soil fertility quality changes appeared to be upward in the Yangtze River Delta. Due to different tillage methods, the phenomenon was found that the soil organic matter was decreased in the first decade,then to be increased in the next decade. For example,the average increasing rate was 17% in the Taihu plain, however, was not obvious in other regions. The content of nitrogen in soil,particular the rapidly available nitrogen,was increased obviously at some type areas. At the same time, the content of rapidly available phosphorus in soil was decreased slowly and cation exchange capacity （CEC） were increased, whereas the content of potassium in soil and pH were decreased obviously. The burden of the soil environment quality was emphasized because of the soil N and P＇s seasonal surplus, particularly,the 30% area ratio of eutrophication.At present, the heavy metals＇ content was also increased, for instances, the velocities of Cu, Pb and Cd were 0.3-1 mg/（kg·a）,0.2-1mg/（kg·a） and 0.3-3μg/（kg·a）.The ecological system is influenced by the organic pesticide,grass killer and surface active agent.