Nitrogen and Phosphorus Loss Law and Emission Reduction Effects Under Water and Fertilizer Management Integrated Mode in Dike Paddy Field

To achieve the purpose of reducing farm non-point source pollution, we integrated site specific nitrogen management precise irrigation, controlled drainage, and wetland eco-repair system in dike area of Taihu basin. During investigation, it had given prominence for the water and fertilizer coupling effects of precise irrigation and site specific nutrient management, the characteristics of integration on controlled irrigation, controlled drainage and wetland ecosystem non-point source pollution control. Then the water and fertilizer integrated management mode of paddy field was put forward in Taihu basin where the water production efficiency increased to 1.64 kg. m-3, water saved 37.8%, fertilizer use efficiency raised 15,4%, yield raised 10%, and N, P load decreased 26%-72%. The modern agricultural and farmland ecosystems that control and cut down the farm non-point source pollution came into being, which can be a reference by Taihu basin to control its agricultural non-point source pollution and eutrophicated water body.

滨岸缓冲带控制农田氮磷流失的作用和机理研究

农田面源氮磷的流失是导致河流湖泊等水体产生富营养化的主要原因之一,其带来的环境、经济及社会问题已引起国内外广泛关注。近年来,关于滨岸缓冲带截留污染物的效率和机理已成为研究热点。文章介绍了滨岸缓冲带在农业面源污染防治上的功能和作用,论述了滨岸缓冲带对氮磷养分的截留转化机理以及稳定同位素技术在机理研究中的应用,讨论了影响滨岸缓冲带截留转化氮磷养分的调控因子,在此基础上就目前滨岸缓冲带控制农田氮磷流失研究中存在的问题提出了未来的研究展望。

典型降雨-稻田排水过程中氮素流失规律

【目的】揭示典型降雨-稻田排水-氮素流失规律,为通过合理制定水肥管理策略减少农田面源污染排放提供理论依据。【方法】以黑龙江省2019年水稻主要生育期(7—9月)内3次典型降雨(降雨量、降雨历时和降雨强度范围依次为56.2~147.6 mm、9~18 d和5.1~8.2 mm/d)过程为研究对象,通过流量自动监测-等比例水样采集装置对典型降雨过程中稻田排水流量进行监测,并在相应时段内对水样进行等比例(排水流量的1/105)采集,分析了典型降雨对稻田排水及其氮素(TN、NH4+-N和NO3--N)流失的影响。【结果】(1)稻田排水量随降雨量的增大而增加,与第1次降雨过程中的稻田排水量(27.2 mm)相比,第2次和第3次的排水量增大了85.8%和154.3%。且排水速率的增加速率远大于降雨强度的增加速率,第3次典型降雨过程中的最大降雨量较第1次典型降雨过程中的值增加了23.0%,但其相应的稻田排水速率峰值却增大了85.3%。(2)典型降雨-稻田排水中的氮素质量浓度在降雨后呈先增大后减小并趋于稳定的趋势,3次典型降雨-稻田排水中的TN、NH4+-N和NO3--N质量浓度范围依次为3.3~14.4、2.3~5.3 mg/L和1.4~4.3 mg/L,均处于地表水水质相应指标IV标准以下。(3)与第1次典型降雨-稻田排水过程中的氮素负荷相比,第2次和第3次稻田排水中的TN、NH4+-N和NO3--N负荷分别增加了1.7~4.6、0.7~1.9 kg/hm^2和0.1~0.9 kg/hm^2。【结论】稻田排水中过高的氮素所导致的农业面源污染排放是黑龙江省水稻主要生育期(7—9月)地表水的主要污染源,避免在强降雨前施肥,并调整降雨后排水时间有助于降低农业面源污染排放。