中文摘要：

在太湖地区采用田间小区试验,对2种灌溉模式（常规连续淹灌与干湿交替节灌）和4种施肥管理（不施氮、常规尿素、控释BB肥与树脂包膜尿素）条件下稻田田面水pH、总氮（TN）、铵态氮（NH＋4-N）、硝态氮（NO-3-N）和亚硝态氮（NO-2-N）的动态变化以及氮素径流流失进行研究。结果表明：田面水pH平均介于6.0~8.4之间,受降雨、施肥和土壤pH的综合影响。田面水氮素以无机形态存在,其中NH＋4-N（浓度0.23~72.01mg/L）平均占TN的61.3%,NO-3-N（浓度0.15~1.79mg/L）平均占TN的18.9%,NO-2-N（浓度0.01~0.24mg/L）平均仅占TN的2.3%。与淹灌相比,节灌虽显著提高田面水TN浓度（15.0%）和NH＋4-N浓度（16.6%）,但大幅降低田间灌溉量（41.9%）和径流量（57.9%）,进而TN和NH＋4-N径流流失量分别降低52.6%和51.8%。施氮显著提高田面水氮素浓度以及NH＋4-N占TN的比例。控释BB肥和树脂包膜尿素较常规尿素处理田面水TN平均浓度分别降低24.6%和78.3%,TN径流流失量分别降低29.4%和32.8%。干湿交替节灌结合控释肥（尤其是树脂包膜尿素）施用有利于降低稻田氮素径流流失,促进农业面源污染减排。

英文摘要：

A field experiment was conducted to study dynamic variations in pH value,total nitrogen（TN）,ammonium（NH＋4-N）,nitrate（NO-3-N）and nitrite（NO-2-N）concentrations as well as runoff loss of N in surface water of paddy field applied with two water regimes（continuous flooding irrigation,alternate wetting and drying irrigation）and four N managements（control,conventional urea,controlled-release bulk blending fertilizer,polymer-coated urea）in the Taihu Lake region.Results showed that the average pH of surface water ranged from 6.0to 8.4,and was affected by the combined effects of rainfall,N fertilization and soil pH.Inorganic-N was the main form of free nitrogen in surface water of paddy field.NH＋4-N（0.23~72.01mg/L）accounted for 61.3%of TN,NO-3-N（0.15~1.79mg/L）accounted for 18.9% of TN,and NO-2-N（0.01~0.24mg/L）accounted for 2.3%of TN.Compared with CF,AWD increased TN and NH＋4-N concentrations by 15.0% and 16.6%in surface water,respectively,however,it decreased the amounts of irrigation and runoff water by 41.9% and 57.9%,thus the runoff loss of TN and NH＋4-N decreased by52.6%and 51.8%,respectively.N fertilization significantly increased TN,NH＋4-N,NO-3-N,and NO-2-N concentrations as well as the proportion of NH＋4-N to TN in surface water.BBF and PCU decreased the average TN concentrations by 24.6% and 78.3%,and then TN runoff losses decreased by 29.4% and32.8%,respectively,in comparison with UREA.Therefore,the combination of AWD irrigation and controlled-release fertilizer（especially the PCU）application could be helpful to decrease the runoff loss of N from paddy field,and promote the reduction of agricultural non-point source pollution.