模拟试验和田间试验的结果表明，铵态氮在春季施入旱地土壤后，其硝化作用速度有慢一快一慢３个阶段。尿素施入旱地后，１周之内即完成水解作用，随之进行硝化作用。两种氮肥完成硝化作用时，正逢雨季，因此，这种转化特点增加了ＮＯ３—Ｎ淋失的潜在危险。在水田条件下，尿素水解稍慢。但不论尿素或碳铵均未检出ＮＯ３—Ｎ存在，淋失的可能性较旱地为小。 The results of simulation and field experiments showed that the ammonium nitrate was slowly, slowly and slowly in three stages when it was applied to dry soil in spring. Urea into the dry land, within 1 week to complete the hydrolysis, followed by nitrification. The nitrification of both nitrogen fertilizers coincides with the rainy season, and this conversion feature therefore increases the potential for NO3-N leaching. Under paddy conditions, urea hydrolysis is slightly slower. However, neither urea nor ammonium bicarbonate detected the presence of NO3-N, and the possibility of leaching was lower than that of dry land.