黄土高原典型流域不同土地利用类型土壤物理性质分析

以黄土高原第三副区典型流域甘肃天水罗玉沟流域为研究区，对其农田、果园、林地和草地4种主要土地利用方式的土壤物理性质进行了分析。结果表明:（1）流域土壤平均含水量为（15.76±0.34）%，各土地利用类型之间存在差异，表现为农田>林地>果园>草地；（2）各土壤平均容重为（1.421±0.034）g/cm³，且均随土层增加而逐渐增加，总体为林地>农田>果园>草地，与含水量有类似分布规律；（3）各土地利用类型土壤孔隙度与其容重呈负相关关系，且总孔隙度、毛管孔隙度及非毛管孔隙度均呈现林地>农田>草地>果园的特征；（4）4种土地利用类型土壤贮水能力存在差异，林地和农田较优，高于果园和草地。值得注意的是，近些年流域大规模坡耕地改水平梯田的生产活动，对农田土壤蓄水保土功能产生较大影响，结果表明农田也具有较高土壤含水量及贮水能力。

Analysis on Soil Physical Properties of Different Land Uses in a Typical Watershed of the Loess Plateau

Soil physical properties of four main land uses (cropland, orchard, woodland and grassland) were investigated on the base of field experiments and indoor measurement from a typical watershed named Luoyugou in the third sub-region of the Loess Plateau. The main findings included: (1) The average soil moisture content was (15.76±0.34)% in the watershed, but it existed obvious differences with regard to different land uses, and presented cropland>woodland>orchard>grassland; (2) The average soil bulk density in the watershed was (1.421±0.034)g/cm³, and tended to increase with soil depth increasing, generally taking on the distribution of woodland>cropland>orchard>grassland, which was similar to the above; (3) Soil porosities of the four land uses had negative correlations with soil bulk densities, besides the total porosity, capillary porosity and non-capillary porosity in each land use all presented woodland>cropland>grassland>orchard; (4) There were some differences on water storage capacity, that is, woodland and cropland took on better performances than grassland and orchard. It should be noticed that in recent years large scale sloping fields were converted to plane terraces, which produced huge influences on soil and water conservation in the cropland, and it was proved to some extent in this paper that cropland had high soil moisture and water storage capacity.