中文摘要：

为了探明盐渍化土壤中尿素N的转化特征,通过室内模拟培养试验研究盐分和施氮量对新疆灰漠土尿素N转化及土壤酶活性的影响。结果表明：尿素N转化受土壤盐度和尿素施用量的影响显著。土壤铵态氮含量随尿素用量和土壤盐度增加而增加,施用尿素可明显提高土壤pH值,促进脲酶活性,加速尿素水解。不施氮肥土壤脲酶活性随土壤盐度增加而显著降低,施氮肥（尿素）土壤,低盐度对脲酶活性无影响,高盐度反而促进了脲酶活性。硝化作用受土壤盐度与施氮量交互作用的影响显著,尿素施用量越大,土壤盐度对硝化作用的抑制越强烈。土壤盐度对硝酸还原酶活性的影响较小,但对亚硝酸还原酶活性有明显的抑制作用。因此,盐度过高以及施用尿素引起的pH值增加可能会导致盐渍土壤中氮肥氨挥发损失增加。

英文摘要：

In order to valuate the transformation characteristic of urea-N in saline soil,a pot experiment was conduced to investigate the transformation of urea-N and soil enzyme activity under different soil salinity levels and urea application rates.The results showed that the transformation of urea-N in soil was influenced significantly by soil salinity and nitrogen rate.The NH4＋-N content of soil increased with soil salinity level and urea application rate increased.The pH value and urease activity of soil were increased by urea application,and hydrolysis of urea was also promoted.The activity of urease was inhibited by soil salinity without urea application,but promoted by high soil salinity under urea fertilization.The nitrification was affected significantly by soil salinity,nitrogen rate,and their interaction.With soil salinity level and nitrogen rate increasing,the nitrification was inhibited intensely.Soil salinity had a slight effect on nitrate reductase activity,but the activity of nitrite reductase was depressed by soil salinity.These results suggested that ammonia volatilization loss could be aggravated in severe salinization soil when urea fertilizer was applied to excess,which can cause soil pH to increase.