自然降雨条件下农田地表产流及氮磷流失规律研究

基于淮北平原自然降雨条件下2个连续汛期观测的降雨-径流试验数据,分析不同试验处理下农田地表产流规律和氮磷浓度及其构成,探讨地表径流氮磷浓度和流失量的时间变化过程及其分布差异。结果表明,当地农田地表径流氮磷浓度构成分别以颗粒态氮和可溶性磷为主,而可溶性氮中又以溶解性有机氮为主,且硝态氮是农田地表径流无机氮流失的主要成分。汛初7月不同土地利用方式下农田地表径流量及铵态氮、硝态氮、可溶性氮磷和颗粒态氮磷的浓度及流失量间的差异相对较小,但8月期间的差异却明显增加,低秆高密度作物种植模式下的相应流失量最低。在淮北平原夏季种植黄豆、棉花等矮秆高密度作物,可起到有效减少地表径流氮磷流失量的作用,减缓因农业非点源污染对地表水体富营养化产生的潜在威胁。

Nitrogen and Phosphorus Runoff Losses from Farmland Under Nature Rainfall

Following the field rainfall-runoff plot experiments in 2007 and 2008 in Huaibei plain, this paper analyzed the temporal variation of surface runoff and various forms of nitrogen and phosphorus from 4 land uses. The results showed that the particulate nitrogen and dissolved phosphorus were the main forms of nitrogen and phosphorus in surface runoff and the dissolved organic nitrogen and nitrate-N were the main dissolved nitrogen and inorganic nitrogen respectively. Concentrations and losses of ammonium-N, nitrate-N, dissolved nitrogen and phosphorus, and particulate nitrogen and phosphorus in surface runoff were generally low in July, while the differences among 4 land uses increased obviously in August and the losses from cotton and soybean plots were the lowest. Thus,the crops such as cotton and soybean, which were dwarf and compact planted, played an important role in alleviating the agricultural non-point source pollution.