稻麦轮作田氮素径流流失特征初步研究

针对近年来氮素化肥施用量大而利用率较低现状，在江苏太湖地区设计田间试验，研究稻麦轮作田全年氮素流失特征。结果表明，在本试验条件下稻季和麦季径流中氮损失量相近，麦季略高，约占施氮量的2％左右。麦稻轮作田径流氮损失中氨态氮较少，以硝态氮和其他形态氮为主，其中氨态氮损失以稻季为主，硝态氮损失稻季和麦季相近，其他形态氮损失麦季较多。不同作物田径流氮组成存在差异，麦季径流氮以硝态氮和其他形态氮为主，氨态氮极少，而稻季在施肥后短时间内径流氮中氨态氮、硝态氮和其他形态氮大致相当，其他时间以硝态氮和其他形态氮为主。

Nitrogen Loss with Runoff and Drainage from Farmland under Wheat-Rice Rotation

Nitrogen is a very important element and has profound effects on crop fields and environment.Aiming at the problem of high application rate but low use efficiency of nitrogen fertilizer,a field plot experiment was conducted in a field of percogenic paddy soil in the Taihu Lake Region under wheat-rice rotation in the years of 2001 and 2002,in order to estimate NO~-_3-N,NH~ _4-N,particulate nitrogen(PN) losses with runoff and drainage.Results indicate that the total N loss is low,about 2% of the N applied,and differs very slightly between the wheat season and rice season.Total N lost via runoff and drainage can be sorted as NO~-_3-N and PN,but the proportions of NO~-_3-N,NH~ _4-N,and PN in the runoff and drainage flows vary from season to season.NH~ _4-N dominates the loss in the rice season whereas PN in the wheat season.The loss of NO~-_3-N does not differ much between the two seasons.NO~-_3-N,NH~ _4-N,and PN losses with runoff and drainage vary sharply with the N application rate,cropping season,growing stage,amount of runoff and drainage.