中文摘要：

对毛乌素沙地南缘半流动沙地、新垫土改良地和改良4年的麻黄地土壤理化性质的研究结果表明：垫土对沙地土壤有明显的改良作用，细粒物质增加，持水能力提高，0～20cm平均粒径由0．24～0．28mm降到0．14～0．18mm。土壤中有机质平均含量为0．107％、全氮为0．0113％，速效氮为11．522mg／kg，分别是半流动沙地的1．67．1．67，2．75倍。改良后通过4年种植的麻黄地土壤得到进一步发育，20～40cm层粉沙含量占到10．38％～18．38％，是新改良地的7．98～14．94倍。有机质平均含量为0．208％，全氮为0．0183％．速效氮为17．658mg／kg，分别是半流动沙地的3．25，2．71．4．21倍，且有机质和全氮含量在30～40cm深处出现峰值。

英文摘要：

The soil bulk density, mechanical composition, water content, the contain of organic matter, the total nitrogen and rapid available nitrogen variations of sandy soil before and after improvement by covering land surface with loess for 15～ 20 cm depth and utilization by planting Ephedra sinica for 4 years in the south edge of the Musu desert were analyzed. Some resuhs are as follows： the water-holding capacity and soil nutrient were on the increase after land improvement. In the layer of 0～20 cm, the bulk density decreased from 0. 254～0. 273 g/cm^3 to 0.15～0. 163 g/cm^3 and the average grain size decreased from 0. 24～0.28 mm to 0.14～0. 18 cm. The water content became higher in the upper layer than in the lower layer. And after the utilization the silt content increased to 7.98～14.94 times. The ratio of the organic matter in the 3 sample plots was 1 ～ 1. 67 ： 3.25～ the ratio of the total nitrogen was 1 ： 1.67 ～ 2.71; the ratio of the rapid available nitrogen was 1 ： 2.75 z 4.,21. On Ephedra sinica sample plot there appeared a peak value of the organic matter and the total nitrogen in the 30～40 cm layer where the root of Ephedra sinica was mainly distributed. The quality of sandy soil has gradually increased with the improvement and the utilization.