冻融交替对砒砂岩与沙复配土壤氮素的影响

目的]探讨冻融作用对毛乌素沙地陕北榆林地区砒砂岩与沙复配土壤氮素的影响,对于提升毛乌素沙地土壤肥力具有重要作用。方法]通过室内培养试验,探讨不同比例砒砂岩与沙复配土壤氮矿化过程对冻融的响应特征。结果]冻融交替作用对土壤氮的矿化有显著影响,在冻融1周期时,3种比例复配土壤中硝态氮、铵态氮含量增加较快。在冻融2周期后,复配土壤中硝态氮、铵态氮含量均出现下降趋势。冻融5周期,复配土壤中硝态氮、铵态氮含量均开始呈现稳定增加趋势。冻融10周期后,1∶1,1∶2及1∶5复配土壤铵态氮含量分别增加了10%,49%与11%,硝态氮含量分别增加了14%,39%与34%,其中1∶2复配土硝态氮、铵态氮含量较1∶1,1∶5增加显著,对氮素的保持性能较好。结论]冻融循环促进了土壤有机氮的矿化,有利于土壤中硝态氮、铵态氮的累积,为早春农作物的生长提供足够的氮素。

Effects of Freezing and Thawing Cycles on Soil Nitrogen of Fieldpathic Sandstone and Sand Compound Soil

Objective] The effects of freezing and thawing Cycles on nitrogen in fieldspathic sandstone and sand compound soil were examined in Yulin area of Northern Shaanxi Province, which was expected to improve soil fertility in Mu Us sandy land.Methods] This paper studied the response of nitrogen mineralization processes in different mixed proportions of fieldspathic sandstone and sand compound soil to freezing and thawing by indoor culture experiment feature.Results] The alternation of freezing and thawing had a signi-ficant effect on the mineralization of soil nitrogen, and the contents of nitrate nitrogen and ammonium nitrogen in three proportions of soils increased rapidly during the first cycle of freezing and thawing. After 2 cycles of freezing and thawing, the contents of nitrate and ammonium in compound soil decreased. In the period of 5 cycles of freezing and thawing, the contents of nitrate nitrogen and ammonium nitrogen in compound soil all began to show stable increasing trend. After 10 cycles of freezing and thawing, the contents of ammonium nitrogen in 1:1, 1:2 and 1:5 compound soil increased by 10%, 49% and 11% respectively, and the contents of nitrate nitrogen increased by 14%, 39% and 34%%. Especially, nitrate nitrogen and ammonium nitrogen contents the 1:2 compound soil were promoted significantly against the ones of 1:1, 1:5 compound soils, it performed better in nitrogen conservation.Conclusion] Freezing and thawing cycles promoted the mineralization of soil organic nitrogen, which was beneficial to the accumulation of nitrate nitrogen and ammonium nitrogen in soil, which can provide sufficient nitrogen for the growth of crops in early spring.