稻田土壤氮素淋失的形态及其在剖面分布特征

Soil profile distribution characteristics of leached nitrogen form in paddy fields

大型原状未扰动稻田土壤渗透计（Ｌｙｓｉｍｅｔｅｒ）定位研究结果表明：淹水条件下淋失的氮素形态主要是硝态氮（ＮＯ－３－Ｎ）；硝态氮在土壤剖面不同深度的数量分布，具有向下递增的特点，并与土壤表层温度有显著的相关性，因而呈季节性的消长变化；有少量铵态氮（ＮＨ＋４－Ｎ）受施肥的影响从耕层土壤向下淋失。

Results of a study under large undisturbed monolith lysimeters of paddy field showed that nitrate (NO_3-N) was the main form of leached nitrogen in percolates after soil flooded for a crop season The changes of nitrate concentration in percolates over the soil profile were characterized by a gradually increasing from the top to bottom and closely affected by the seasonal temperature Meanwhile, leaching loss of ammonium N (NH+4-N) was much less than that of nitrate-N, which was rich amount only in upper soil layer and was substancially increased by nitrogen fertilization The concentration of NH+4-N in percolates decreased by the deepened depth over the soil profile