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1 基本原理 几乎所有的土壤物理、化学、生物过程都与土壤中的水分运动有关。而支配土壤水分运动的土壤内在因素主要是土壤的持水特性和导水特性。因此,土壤的这两个物理特性直接关系到植物对土壤水分的利用、对土壤营养物质的吸收和对土壤中有害物质的排斥。总而言之,土壤的持水特性和导水特性属生态学研究者所关心的最关键的问题之列。所谓持水特性,是指土壤的基质势h与土壤体积含水率θ之间的关系。而导水特性则是指导水率K(单位水势梯度作用下水流过垂直于梯度方向的截面上的通量密度)与θ之间的关系。这两个关系一般是非线性的,因此需要作不同含水量的基质势和导水率的测量。通常情形下,测定基质势的方法有
1 Rationale Almost all of the soil’s physical, chemical, and biological processes are related to the movement of water in the soil. The inner factors controlling soil moisture movement are mainly soil water holding characteristics and water conducting characteristics. Therefore, these two physical properties of soil are directly related to the plant’s utilization of soil moisture, the absorption of soil nutrients and the exclusion of harmful substances in the soil. All in all, the water-holding and water-holding properties of soils are among the most critical issues of interest to ecological researchers. The so-called water-holding characteristics, refers to the relationship between soil matrix potential h and soil volumetric moisture content θ. The water-conducting property refers to the relationship between the water conductivity K and theta (the flux density of the water flowing through the cross-section perpendicular to the gradient direction under the unit of water potential gradient). These two relationships are generally non-linear and therefore require measurements of matrix potential and hydraulic conductivity for different water contents. Under normal circumstances, the method of determining the matrix potential