水肥综合管理对减少滇池北岸韭菜地氮磷流失的研究

农田氮、磷随地表径流向水体迁移,不仅造成化肥利用率降低,农业生产成本上升,还对水环境造成污染,引起水体富营养化.针对滇池流域规模化韭菜生产施肥量大,农业面源污染严重等问题,采用田间试验,结合自然降雨与人工模拟降雨,研究了不同施肥及田间沟渠利用方式下农田氮、磷的流失风险.结果表明,相对于化肥表施,合理的有机-无机肥料配合施用以及化肥深施,可分别降低地表径流中总氮和总磷平均浓度53%和39%.施肥后1周为氮、磷流失的高风险期,随后其风险随时间延长而降低;通过小区间沟渠的改造,提高排水溢流口高度,控制径流在沟渠内滞留时间以及采用农田养分循环利用的回灌技术,可减少农田向环境水体输出总径流量的76%以上,并同时提高了肥料利用率.

Integrated Management of Water and Fertilizer to Reduce Nitrogen, Phosphorus Loss from Chinese Chive Field in the North Bank of Dianchi Lake

The nitrogen(N) and phosphorus(P) release to surface waters from farmland not only leads to the declining of utilization rate of fertilizer, but also results in the raising of agriculture cost, as well as leads to the pollution and eutrophication of freshwater bodies. Effects of different fertilizing modes and ditch utilization patterns on controlling the pollution N and P from surface runoff in connecting with high chem-ical fertilizer dosage applied in Dianchi Lake region were investigated through field experiment with natural and artificial simulated rainfall. The result showed that compared with surface application of chemical fertilizer,right amount manorial together with chemical fertilizer, and subsoil fertilization could reduce the concentration of total nitrogen(TN) and total phosphorus(TP) in runoff by 53% and 39%. The first week after fertilization was the main duration of N, P loss by runoff, then, the risk reduced by time. Recycle nutrients and water in runoff back into the field through rebuilded ditch could reduce the amount of runoff more than 76%, as well as increase the utilization rate of fertilizer.