陕西省靖边县不同土层含水量与干层差异研究

根据野外考察和土层含水量的测定，研究了靖边县沙地土层和黄土层土壤含水量。结果表明，靖边几个研究点的沙地土层平均含水量小于3%，杨树林地黄土层平均含水量为7％左右；沙地土层含水量远低于黄土层含水量，杨树林沙地和沙柳沙地已经出现了严重的土壤干层，杨树林地黄土层出现了发育中等的土壤干层，干层发育深度都已超过6m。干旱气候是引起干层发生的主要因素，人工灌木和树种消耗水分较多也促进了干层的发育。沙地区应以发展耐旱草灌为主的植被，黄土分布区也应发展草灌为主的植被，但在黄土分布的洼地区和有外来水源的地区可以发展耐旱的乔、灌、草相结合的植被。在靖边县这一土壤干层发育较严重的地区，造林一般不能带来良好的环境效益与经济效益，反而会导致深部土壤水分的过量消耗等不良后果，因此该区是不适于造林的地区。

Research on Water Content and Dried Soil Layer in Jingbian County of Shaanxi Province

Water contents of sandy soil and loess in Jinghian County, Shaanxi Province are studied through the field investigations and measurements. Experimental results show that water content of sandy soil is less than 3% and water content of loess under poplar trees, about 7%. Severe dried layer occurs in sandy soil and moderate dried layer under poplar trees, in loess. All the dried layers are above 6 m in depth. The degree and depth of dried layer indicate that natural arid climate is a dominant factor causing dried layers in the area, with the tree species being an important factor. During ecological and environmental construction, different types of vegetation should be recovered in view of the different levels of dried layer development. Grass and bush should be planted in the sandy soil area and grass and drought tolerant bush with trees should be planted in the loess soil area. Where dried layers develop severely, afforestation is unsuitable because it can not bring environmental and economical benefits, but can cause excessive consumption of deep soil moisture and underground water.