环竺山湾湖小流域种植业面源污染减排潜力研究

农田面源污染一直被认为是竺山湾湖水质恶化的重要因素之一。采用实地调研农户的方法考察了环竺山湾湖小流域粮食作物(水稻、小麦)、蔬菜、果园生产在"十二五"初期养分投入状况,结合太湖流域"十一五"期间已获示范验证、可推广应用的环境友好型种植技术模式或实践,估算了环竺山湾湖小流域种植业生产控污减排能力。结果表明,基于目前的稻麦、蔬菜和果树种植面积,规模化应用稻-麦施肥减量技术和稻-绿肥技术轮作模式可分别实现无机N投入减量132.4、424.3 t·a-1和总N减排20、42.3 t·a-1;蔬菜种植优化技术模式可减少无机N投入993.7 t·a-1和减排总N 181.3 t·a-1;果园优化施肥与三叶草截流控害集成技术模式,至少可实现节省无机N投入1000 t·a-1和减排总N 116.8 t·a-1。综上,环竺山湾湖小流域种植业生产已较"十一五"时期无机N投入水平明显降低,但依然还有减量空间;有机肥施用量逐步提升,但符合竺山湾湖小流域的最适施用水平还有待深入研究。最后给出了环竺山湾湖小流域农田面源污染规模化防控建议,以期为改善竺山湾湖水质进而确保太湖水质安全提供支持。

Potential of mitigating nonpoint source pollution from farmlands around Zhushan bay in Tai Lake watershed

Farmland nonpoint source pollution has been recognized as one of the important factors deteriorating water quality of Zhushan bay in Tai Lake watershed. Those growers planting grain crops, vegetables and fruits around Zhushan bay were interviewed on nutrient inputs to fa rmlands. Based on the environmental-friendly agricultural technology practices that were demonstrated, verified, and regionally extended during the 11th five-year planning period, the potential of mitigating nonpoint source pollution from farmlands around Zhushan bay in Tai Lake watershed was estimated. Results showed that, under the current acreage of growing rice-wheat, vegetables and fruits, the large-scale applications of environmental-friendly agricultural technology practices, i.e., rice-wheat fertilization reduction technology and rice-green manure rotation pattern, could further reduce inorganic N inputs by 132.4 t·a^-1 and 424.3 t·a^-1, and mitigate the total N load of 42.3 t·a^-1 and 20 t·a^-1, respectively; vegetable optimized planting mode could realize a reduction of 993.7 t·a^-1 inorganic N and a mitigation of 181.3 t·a^-1 total N; orchard integration mode of optimum fertilization, run-off, and pest control with clover could cut at least 1000 t·a^-1 of inorganic N inputs and mitigate 116.8 t·a^-1 of total N surface runoff loss. Compared with the 11th five-year planning period, the present results also showed that increasing uses of organic fertilizers could additionally reduce inorganic nitrogen inputs in local farmland. However, further re search is necessary to find the most appropriate application level of organic fertilizers for the region. This study also proposed a scale pre vention and control of farmland nonpoint source pollution around Zhushan bay in Tai Lake watershed in order to provide supports for water quality safety of Tai Lake.