土壤气态水扩散特征初探

在室内模拟试验的基础上，对旱地不同土层土壤气态水扩散特征进行了探讨，初步推断：①在小于最大吸湿量时，土壤中也存在非气态的水分运移，但气态的水分扩散一般是主要机制；②粘粒含量较高、比表面积较大的土壤中非气态水分扩散所占比例较大；③温度升高，扩散系数增大，④扩散也明显存在滞后现象；⑤对供试土样，在相对水气压约４０％的含水量下，气态水分扩散系数达最大值。

The Characteristics of Vaporous Water Diffusion in Soil

Based on the in-lab simulation experiments,the characteristics of va-porous water diffusion in soil samples from different layers in rainfed farmland were dis-cussed with some deductions obtained in the following :(1)there exists a water move-ment of non-vaporous phase in soil in the case of less than the maximum adsorptive ca-pacity, but the vapor diffusion is the main mechanism in general; (2)the non-vaporouswater diffusion consists of greater proportion in soil of high clay content and large spe-cific surface area;(3) when the temperature goes up,diffusion coefficient increasesl;(4)the noticeable hysteresis effect exists in water vapor diffusion ; and(5) vapor diffusioncoefficients in the testing soil samples reach the maximum value in the case of vvater con-tent of about 40% of relative vapor pressure.