烤田对土壤中氮素和与氮有关的酶活性影响

在水稻分蘖期对5种不同尿素氮肥水平的小区进行烤田5天的试验。试验结果表明,在烤田过程中,脲酶活性变化不明显,呈微弱增加趋势。硝酸还原酶活性急剧降低,羟胺还原酶活性呈波动变化,几乎检测不到亚硝酸还原酶活性。土表的铵态氮也呈波动变化,随着烤田时间的增加铵态氮含量降低。土表的硝态氮浓度不断增加,烤田增大了复水后硝态氮向地下水淋溶的趋势。施氮量越多,土表的矿质氮含量也越多。土壤烤田的主要目的是通过降低土壤的含水量,提高土壤的氧化还原电位,改善土壤的通气状况。

Effects on Nitrogen Content and N Transfermation Related Soil Enzymes Activities in Soil Drying

The experiments conducted in fifteen small compartments with five different urae levels to dry soil in rice tiller for five days. The experiment results showed that urease activity had no obvious variance and the trend increased slowly. Nitrate reductase activity decrease quickly, and hydroxyamine reductase activity fluctuated, in addition we almost couldn't get the nitrate reductase activty in soil drying. The concentrate of ammonium-N fluctuated in soil surfaceand decrease as the delay of soil drying. The concentration of nitrate-N increased continuously in soil surface, which resulted in nitrate leaching to groundwater after rewetting. If soil was fertilized more urea mass, then the mineralizable N content was higher in soil surface. The aims of soil drying were that reduce the soil water content, advanced soil redox potention(Eh) and improved the conditions of soil aerating.