黄土高原退耕还林土壤的理化性质

Soil Physicochemical Properties in Loess Plateau

为探明黄土高原农田退耕后土壤理化性质的变化，选取同一坡面上的农田、退耕柠条林和刺槐林，比较分析了其80 cm深度土壤中水分含量、碳酸钙、pH 和粒度。结果表明：与两林地比较，农田土壤含水量最大，容重最低；碳酸钙含量为柠条林＞农田＞刺槐林，农田退耕为柠条林后，碳酸钙含量增加，深度分异减小；pH值含量为刺槐林＞柠条林＞农田，三样地pH值随深度增加而增加；土壤0．2 mm以下粒径三样地差异不明显，0．2～1 mm粒径两林地明显高于农田。尽管农田退耕后土壤含水量降低，但大粒径土壤含量的增加说明土壤质量转好，三样地碳酸钙和pH的不同变化说明两者的影响因素有差异。

To explore the changes of the soil physicochemical properties after cropland was restored, the author chose the three sites of cropland,restored R.pseudoacacia forest and restored C.korshinskii Shrubwood,and analyze the soil water content,density,calcium carbonate,pH values,particle sizes in a depth of 80 cm.Results：Compared with the two forest sites,the soil water contents of cropland site are the highest in all depths, and soil densities are the lowest;The calcium carbonate value suggests C.korshinskii shrubwood＆gt;cropland＆gt;R.pseudoacacia forest,when cropland turned into C.korshinskii shrubwood,calcium carbonate value increased,no obvious depth-distribution was indicated;The pH value followed the sequence of R.pseudoacacia forest＆gt;C.korshinskii shrubwood＆gt;cropland,increased with depth in each study site;Though no obvious difference was suggested for the particle size lower than 0.2 mm,those of 0.2~1 mm were lower for cropland than other sites.After cropland was restored, though the soil water content decreased,the increase of big particle size suggested that soil quality raised, and the different changes in three study sites between calcium carbonate value and pH value suggested different relative factors.