应用大型原状土柱渗漏计测定冬小麦-夏玉米轮作期硝态氮淋失

从 1998— 2 0 0 0年 ,利用土壤溶液提取器和大型原状土柱渗漏装置 (面积 0 18m2 ,2m深 )田间观测了北京地区冬小麦 夏玉米轮作期间的NO-3 N淋失 .设置对照和常量氮肥水平两个处理 .土柱渗出液的NO-3 N平均浓度 ,对照处理为 35 0mg L ,常量施氮土柱为 5 5 6mg L ;NO-3 N淋失通量 ,对照处理为 1 3g (m2 ·a) ,常量施氮土柱为 2 0g (m2 ·a) ;氮肥表观淋失百分数分别为 10 %、0 86 %和 0 5 4%,受年降雨变化的影响非常明显 .常量氮肥施用条件下 0— 2 0 0cm土壤提取液和土柱底部渗出液的NO-3 N浓度 ,都超过饮用水卫生标准 10mg L ,因此 ,常量施氮水平引起的硝态氮对浅层地下水的污染不容忽视 .

Soil core lysimeter study of nitrate leaching from a winter wheat-summer maize rotation

An array of porous cup samplers and two large undisturbed soil column drained lysimeters (0.18m² surface area, 2m deep) were used to examine NO₃^- leaching from 1998 to 2000. The field experiment was designed to study NO₃^- losses from continuously, fertilized (at a rate corresponding to 240kg(N)·ha^-1) winter wheat/summer maize rotation in Beijing area. The average flow-weighted leachate concentrations of three years were in range of 35.0 and 55.6mg(NO₃^--N)·L^-1 for the non-fertilized soil column and the fertilized N soil column respectively. The average masses of NO₃^--N leached of three years were 1.3 and 2.0g/m² for the non-fertilized soil column and the fertilized N soil column respectively. The loss percentages of N fertilizer applied were 10% and 0.86% and 0.54% in 1998, 1999, and 2000, respectively, which were significantly controlled by precipitation. Application of N fertilizer resulted in excessive nitrate N leaching, and the solution and leachate, exceeded the maximum contaminant level of 10mg/L.