南水北调中线水源区退耕地土壤理化特性研究

Soil Physicochemical Properties on Returned Farmlands in the Water Source Area of the South-to-North Water Diversion Project

以南水北调水源区陕西省宁陕县寨沟小流域为例,选择退耕还林区退耕2,5,9,12和16 a的5块样地以及作为对照的坡耕地,对其土壤含水量、容重、孔隙度和有机质进行了采样测定。结果表明,退耕5,9,12,16 a的土壤物理性状较坡耕地有明显改善。其中土壤含水量、孔隙度和有机质均表现为逐渐增加的趋势,土壤容重则随着退耕年限的增加不断减小。而退耕2 a的土壤水分、物理状况与坡耕地相比没有明显改善。随土层深度的增加,土壤含水量、孔隙度和有机质呈逐渐减少、土壤容重呈逐渐增加的趋势。说明通过退耕还林,能够使坡地土壤肥力和保水、蓄水能力得到改良,抗侵蚀能力得以增强,但必须有较长的退耕恢复时间,才可能有明显变化。

Soil water content, bulk density, porosity, and organic matter on five abandoned farmlands （2, 5, 9, 12, and 16 years） are studied by contrasting with slope farmland in Zhaigou District of Ningshan County. Results show that soil physicochemical properties on four returned farmlands （5, 9, 12, and 16 years） are better than slope farmland. Soil water content, porosity, organic matter, and bulk density are improved with rehabilitation time, whereas soil physicochemical properties in the 2 year returned farmland do not change obviously. Soil water content, porosity, and organic matter are reduced with increased soil depth and however, bulk density is on the contrary. This suggests that soil fertility, water retaining capacity, storage capacity, and anti-erosion ability can be improved by returning farmland to forest, but it will not make significant changes in a short time.