不同氮肥管理模式对太湖流域稻田土壤氮素渗漏的影响

EFFECTS OF NITROGEN MANAGEMENT ON NITROGEN LEACHING OF PADDY SOIL IN TAIHU LAKE REGION

针对太湖流域稻田土壤氮素流失引起的面源污染问题,以农户常规施肥处理、化肥减量施肥处理、缓控释肥处理、有机无机肥配施处理以及按需施肥处理5种稻田氮肥管理模式,探讨了不同施氮水平与肥料类型的处理对20～40 cm、40～60 cm、60～80 cm以及100～120 cm四个深度土壤氮素渗漏的影响。结果表明,20～40 cm渗漏液中总氮(TN)浓度与施肥量成正比;农户常规施肥处理会出现40～60 cm TN浓度高于20～40 cm的现象;缓控释肥处理具有较高的20～40 cm TN淋失量;溶解性有机氮(DON)是稻田氮素进入地下水的主要形态,占TN的60%～70%;减少33%的氮素施用量,可降低进入地下水体36.9%～49.0%的TN浓度。按需施肥处理能在保证产量的情况下降低施氮水平,减少氮素渗漏损失,是适宜该地区的环境友好型氮肥管理模式。

A field experiment,directed against non-point source pollution brought about by nitrogen leaching from paddy field in Taihu Lake Region,was conducted to study effects of nitrogen management on nitrogen leaching from paddy field at depths of 20~40 cm,40~60 cm,60~80 cm and 100~120 cm.The experiment was designed to five patterns of nitrogen management,i.e.Site-specific nitrogen management（SSNM）,Organic chemical N combined application（OCN）,Controlled release urea application（CRU）,Reduced chemical N application（RCN） and Farmer＇s common N application（FN）.It was found that in the soil layer（20~40 cm）,TN in the leachate was positively related to N application rate,and CRU has more TN leakage amount.Compared with the other treatments,FN treatment had a higher concentration at 40~60 cm than 20~40 cm depth.DON was the prime form of N leaking into ground water.TN concentration of leachate at 100~120 cm depth would decrease 37%~49% if N input was reduced by 33%.Site-speecific nitrogen management,which could reduce N leaching without sacrifice of yield,would be environment-friendly nitrogen management methods for Taihu Lake region.