太湖地区农田土壤养分动态及其启示

Agricultural Soil Nutrient Status in Taihu Lake Area and Its Implication to Nutrient Management Strategies

太湖地区人地关系紧张 ,环境问题尤其是地表水体富营养化严重 ,农田生态系统的养分收支和土壤养分状况不仅关系到农业的高产稳产 ,对区内的水环境质量也有着重要的影响。典型区的实地调查和采样分析结果表明 ,自 2 0世纪 80年代初以来太湖地区农田生态系统中的氮、磷一直处于盈余状态 ,且盈余量不断增加 ,土壤钾素则长期亏缺 ,但近年来有所缓和。区内土壤有机质、全氮、全磷和有效磷含量近 2 0年来都有较大幅度的提高 ,速效钾含量在 2 0世纪 90年代中期以前呈下降趋势 ,近年来有所回升。主要类型土壤的pH也呈降低的趋势。

Taihu Lake watershed region is one of the most densely populated areas in China and is confronted with numerous environmental problems, especially fresh water eutrophication. It is of crucial importance to improve soil nutrient management practices in order to have a positive effect on nutrient use efficiency, crop yield, and the environment. Nutrient balances of different times were calculated for arable soils in a case area. It was shown that positive balances for nitrogen and phosphorus and a negative balance for potassium had lasted for decades. Results of representative soil sampling between 1982 and 1999 show that decades of fertilization at rates exceeding the amount removed by crops have resulted in widespread accumulation of nitrogen and phosphorus in the area. Until recently the soil potassium level had declined due to the insufficient input. Soil pH of most samples also decline and this may be attributed to the over use of chemical fertilizer. Based on the analysis of the characteristics of nutrient budget and soil nutrient dynamics of the area some nutrient management options were proposed in the paper.