风沙区柠条沙堆土壤有机质及酶活性特征研究

摘要

为探索柠条(Caragana korshinskii)沙堆土壤有机质及土壤酶活性的空间异质性,选取不同大小的柠条沙堆,对其顶部、中部及底部的有机质含量、土壤酶活性变化情况进行分析研究.结果显示:(1)土壤pH值及含水量与柠条灌丛沙堆的大小没有明显的规律,在沙堆不同部位之间差异不显著;土壤有机质随沙堆的增大而减少,且10~20 cm土层沙堆顶部的有机质含量显著高于中部和底部.(2)土壤脲酶与蔗糖酶活性随沙堆的增大而降低,磷酸酶与过氧化氢酶活性随沙堆的增大表现为先升高后降低,4种土壤酶活性基本上由沙堆的顶部向底部递减,随着土壤深度的增加,土壤酶活性显著降低.(3)沙堆的大小、土壤pH值及土壤含水量与蔗糖酶活性均存在显著负相关关系,与磷酸酶活性之间存在极显著负相关关系;土壤有机质含量与过氧化氢酶活性之间无明显相关性,与其他3种酶活性之间呈极显著正相关关系.研究表明,柠条能够改善沙堆上的土壤养分,提高土壤酶活性,对荒漠区退化土壤具有改善作用,但随着沙堆的发育这种作用逐渐降低.%To study the spatial heterogeneity of soil organic matter (SOM) and soil enzyme of Caragana korshinskii shrub nebkhas,we evaluated the content of SOM and enzyme activities (urease,saccharase,phosphatase,catalase) of different size C.korshinskii shrub nebkhas in three positions (the top,the middle and the bottom of nebkhas).The results indicated that: (1) the different sizes of nebkhas had no significantly effect on content of soil water moisture and pH value and it had little different among top,middle and bottom positions.The content of SOM decreased with the nebkhas development.The SOM content of top is higher than that of others obviously.(2) The activity of urease and saccharase decreased with the nebkhas development,while phosphatase and catalase first increased and then decreased.The soil enzyme activities decreased from top to bottom of nebkhas.The soil enzyme activities decreased with soil depth.The soil pH value,nebkhas size and soil water moisture were shown significant negative relation to soil saccharase enzyme activities(P <0.05),while had very significant negative to phosphatase.The SOM content had no correlation with catalase,while had very significant positive to others.These results suggested that C.korshinskii could increase soil nutrient and enhance soil enzyme activities.Caragana could play a vital role in soil recovery in a graded area of a desert zone and gradually reduced with the development of the nebkhas.