中文摘要：

以东北黑土为试验对象,通过室内模拟实验,研究了淹水-风干过程中土壤氮素转化和土壤酶活性的变化规律,并初步分析了其作用机理。结果显示在8个淹水-风干周期内,各处理组（包括对照组）的铵态氮（NH4^＋-N）和硝态氮（NO3^--N）含量均呈下降趋势,其中经过干湿交替处理的土壤NH4^＋-N和NO3^--N含量高于对照组;总的来看,经历干湿交替的实验组土壤氨化速率、矿化速率和硝化速率均高于恒定含水量的对照组。受土壤水分和干湿交替的影响,脲酶活性总体表现为：实验组〉对照组（0.5、3周期除外）;转化酶活性整体上也表现出相同的变化规律,仅在培养的第8周期对照组转化酶活性高于实验组。综上,干湿交替可促进黑土区土壤氮素的转化以及土壤脲酶和转化酶的活性。

英文摘要：

The northeast black soil is typically characterized by drying- rewetting cycles,simulation experiments were conducted to discuss the change rule of flooded- air drying on nitrogen transformation and soil enzyme activities,and the mechanism was analyzed preliminarily. The results showed that the contents of ammonium nitrogen and nitrate nitrogen decreased during the whole experiment; the ammonium nitrogen and nitrate nitrogen contents under the dry- wet cycle treatments were higher than that of control group. Overall,ammonifying,mineralization and nitrification rate,which experienced drying- rewetting cycle were higher than that of control group with constant water content. The activities of urease presented in the following order： the experimental group 〉the control group,which obviously affected by the soil moisture and drying- rewetting,except the 0. 5 and 3round in the experiment. While,invertase activities also showed the same trend,only in the 8 training cycle,the control group was higher than the experimental group. In conclusion,drying- rewetting conditions can promote the nitrogen transformation of black soil and soil urease and invertase activities.