稻田化肥减量施用的环境效应

Effects of reduced fertilizer application on environmental quality of paddy field

在太湖地区宜兴市水稻田采取田间试验与室内分析相结合的方法，研究了适当减少化肥用量（优化施肥）对水稻产量、田面水与渗漏液中氮、磷养分的影响。结果表明：优化与常规两种施肥处理下水稻产量差异不显著，但优化施肥节省22％氮肥，减少30％～40％氮素径流损失，减少32．3％氮素渗漏损失。田面水与渗漏液中溶解性总氮（TDN）浓度与施肥量呈正相关，在施肥后的1～2d内达到峰值，不同施氮处理TDN浓度在一周内差异显著，以后渐趋一致。施肥后田面水中溶解性总磷（TDP）浓度高达15．7mg·L^-1，整个稻季均高于导致水体富营养化的临界值，存在着污染附近水体的风险；稻田对灌水中的磷有净化作用。适当减少化肥用量、加强稻田水肥管理，是控制农田面源污染的重要措施。

A paddy field in the Tai Lake region of Yixing County was selected to study the effects of reduced fertilizer application on rice yield, nitrogen and phosphorus concentrations in surface water, leachate through field trial and indoor analyses. The results show that rice yield under optimum fertilization treatment does not significantly differ from conventional fertilization treatment, and that optimum fertilization saves N-fertilizer by 22% and reduces runoff N by 30% - 40% , and leaching N by 32.3%. Total Dissolved Nitrogen （TDN） concentration in surface water and leachate increase with N-fertilizer application rate, with peak concentrations occurring 1 - 2 days after fertilization. A significant difference in TDN is observed between two fertilization treatments within one week after fertilization. Total Dissolved Phosphorus （TDP） concentration in surface water during the rice growing season exceeds critical value of water eutrophication by a merging as high as 15.8 mg· L^-1 after fertilization, leading to pollution of surrounding surface water. Paddy field is able to filter P in irrigation water. It is therefore believed to reduce fertilization to appropriate rates and rationally manage fertilizer and water are important measures to control non-point source pollution in agriculture.