土壤盐碱化问题是当今土壤退化的主要问题之一。为了研究覆沙厚度对盐碱地土壤理化性状和微观结构的改善效果，于2013年，在富平中试基地，在盐碱地耕作表层，覆盖厚度分别为0、5、7、9、11、13和15 cm的沙子，并且与盐碱地耕作层30 cm充分混合，在种植5年，小麦收获后，分析测定0~60 cm土层土壤的pH、全盐量、Na+含量、有机质含量和微细观结构。结果表明：1) 覆沙处理可有效改善盐碱地土壤pH和全盐量，以覆土厚度为15 cm最佳。2) 每个处理下，随着土层深度的增加，Na+离子含量随着土壤土层深度的增加变化不显著(P < 0.05)；3) 覆沙盐碱地较未覆沙可有效提高盐碱地土壤下层有机质含量；4) 通过分析覆沙厚度为0、5、9和13 cm的盐碱地，土壤颗粒化效果明显，孔隙度增加，有力地破除了盐碱地的板结现象。综上所述，覆沙15 cm整体改善土壤效果最佳，覆沙5 cm和7 cm对20~30 cm中层土壤理化性质改善效果最佳。
Soil salinity problem is one of the main problems of soil degradation. In order to study the sieved sand thickness of saline-alkali soil physical and chemical properties and microscopic structure improvements, in 2013, in Fuping experimental base, in the salty soil tillage surface, cover thick-ness respectively 0, 5, 7, 9, 11, 13 and 15 cm of sand, and saline-alkali soil magnetism 30 cm mix, in five years later, after wheat harvest, the analysis was developed for the determination of 0 - 60 cm soil layer soil pH, total salt, Na+ content, organic matter content and tiny view structure. Results show that: 1) the sieved sand treatment can effectively improve the saline-alkali soil pH and total salt, of which covered with soil thickness 15 cm is the best; 2) under each processing, with the in-crease of soil depth, Na+ ion content changes with the increase of soil depth of soil layer were not significant (P < 0.05); 3) the sieved sand sagebrush and less sieved sand can effectively improve the saline-alkali soil organic matter content of the lower; 4) by analyzing the sieved sand thickness of 0, 5, 9 and 13 cm, saline-alkali soil granular effect is obvious, porosity increases, breaking the powerful harden phenomenon of the saline-alkali land. To sum up, sieved sand 15 cm, overall im-proving soil effect is the best, sieved sand 5 cm and 7 cm, soil physical and chemical properties of 20 - 30 cm middle improved effect are the best.