太湖地区农田土壤中硝态氮垂直运移的规律

用模拟土柱和田间定期采样的方法对太湖地区农田土壤中硝态氮垂直运移规律进行了研究.结果表明,在饱和条件下,硝态氮垂直运移过程的穿透曲线呈现不对称形状和拖尾现象,主要由于土壤中存在着动水和不动水的比例不同和土壤的物理性质所致.在非饱和条件下,硝态氮运移过程的时间明显加长,穿透曲线的峰值增高,优先流不明显,穿透曲线平缓.与硝态氮结合的阳离子价数对硝态氮的垂直运移没有影响.试验区的硝态氮在土壤中的含量随季节的不同而呈现规律性的变化,冬、春季硝态氮在土壤中的含量较高;夏、秋季则较低.地下水中的硝态氮污染现象不显著,主要由于土壤质地黏重,阻碍了硝态氮向地下水中的运移.

Study on the nitrate vertical transport rule in farmland soil of Tai Lake area

The nitrate vertical transport rule in farmland soil of Tai Lake area was studied. The results showed, the breakthrough curve of nitrate vertical transport in saturated condition was more or less non-symmetrical, mainly due to the different proportion of mobile and immobile water in the soil and soil physical properties. Under unsaturated condition, the duration of the transport process was obviously prolonged, peak value of the breakthrough curve raised, the preferential flow was not significant and the curve was gently. The valence of cation combined with nitrate had basically no influence on the nitrate vertical transport. The content of nitrate in studied soils showed regular changes with seasons, higher in winter and spring than in summer and autumn. No marked nitrate pollution in the groundwater was found, mainly because the nitrate transport to underground water was impeded by the heavy clay soil.