北京地区潮土表层中NO3^——N的转化积累及其淋洗损失

NO -N TRANSFORMATION ACCUMULATION AND LEACHING LOSS IN SURFACE LAYER OF CHAO-SOIL IN BEIJING

本试验利用渗滤池设施，采用化学分析和同位素技术相结合的方法研究了北京地区潮土表层中施用氮肥后ＮＯ－Ｎ的转化积累及其１３０ｃｍ土体的淋洗状况。常规分析结果表明，在春小麦和夏玉米的生育前期可以观察到氮素明显地向ＮＯ－Ｎ的转化积累，其强度随尿素施用量的增加而明显增加，而尿素、硝铵、硫铵等不同氮肥品种处理之间有差异但大多不显著。同时夏玉米期间转化积累作用比春小麦期间强烈。￣（１５）Ｎ标记试验结果表明，在春小麦生育前期氮素向ＮＯ－Ｎ转化积累的过程中，同时发生了肥料氮的固持和损失，并且土壤本身氮素在这种转化过程的初期占有优势。ＮＯ－Ｎ淋洗出１３０ｃｍ土体主要发生在降雨集中季节，淋失量与同期降雨量线性相关显著；淋失水中ＮＯ－Ｎ含量在施氮肥的处理区大多超过饮用水卫生标准即１０ｍｇＮＯ－Ｎ／Ｌ的限额，平均含量最高可达３３ｍｇＮＯ－Ｎ／Ｌ，这对本地的地下水会造成短期的硝酸盐污染。但是淋洗损失的总量不高。

In lysimeters, the transformation and accumulation of NO-N in surface layerand its leaching loss out of 130cm solum column in chao soil in Beijing were studiedby the routine analysis methods in combination with isotopic technique. The resultsshowed that N transformation to NO-N could be observed during tbe earliergrowth stage. The significant differences existed among the treatments applied at 3rates of urea but could not be found among the those with 3 kinds of N fertilizers.And the transformation to NO -N was less strong during spring wheat growthperiod than during summer corn growth period. Meanwhile immobilization anduncounted loss of fertilizer N could occur.NO-N could be leacked out of 130cm soil body during rainy season withmore than 10mg NO-N/L in the fertilized lysimeters where the mean NO-Ncontent might be up to 33 mg/L. And NO-N leaching loss was significantly corre-lated to the precipitation. However, the total leaching loss rate of fertilizer N wasnot high.