颗粒组成对包气带水分运动参数的通径分析

摘要

颗粒结构组成是反映土壤质地的重要特征，决定着土壤的水力参数，进而对热量、水分和化学物质迁移过程起主导作用。为揭示土壤颗粒组成对水分运动参数的作用效应，通过灌溉前后不同时空野外试验采样、实验室分析，应用相关分析与通径分析相结合的方法，研究了不同深度(0.1~6m)的砂粒、粉粒、粘粒含量对土壤水分运动参数影响。结果表明：粘粒含量是影响土壤残余含水率(θr)最重要的正作用因子，其次是砂粒含量的负作用；粉粒含量是影响土壤饱和含水率(θs)最大的正作用因子，并对砂粒传递间接的负作用，其次是砂粒含量的负作用，粘粒含量对其没有影响；影响土壤水分特征曲线形状参数α最大的正作用因子是粉粒含量，其次是砂粒含量的负作用和粘粒含量的正作用；影响土壤水分特征曲线形状参数n最大的正作用因子来至于砂粒和粉粒含量，而粘粒含量的正作用也不能忽视；对土壤饱和导水率(ks)影响最大的是砂粒含量的正作用，其次是粉粒含量的正作用和粘粒含量的负作用，同时粘粒含量通过砂粒传递的负作用对其产生影响。砂粒和粘粒对土壤水分特征曲线形状参数n的影响显著，砂粒对土壤饱和导水率直接影响较大，而粉粒和粘粒分别对土壤饱和含水率、残余含水率影响明显。表明通径分析能够透过简单相关的表面深入研究自变量与因变量之间的因果关系，揭示各个因素之间的相对重要性和传递影响。%Soil particle structure reflects the im portant characteristics of soil texture, determines the soil hydraulic parameters, which plays a leading role for heat, moisture and chemical migration process. In order to reveal the effects of soil structure on water movement parameters,we used space-time field test before and after irrigation sampling, laboratory analysis and path analysis method to studythe influence of soil hydraulic properties on sand, silt and clay content of vadose zone soil by the path analysis. The results showed that the clay content was the most important positive factor affecting the soil residual moisture (θr), and the sand content was the second negative factor. The silt content was the most important positive factor affecting the soil saturated water content (θs)and transferred the indirect negative influence, the sand content was the second negative factor, while clay content had no effect on it. For the soil water characteristic curve shape parameter (a), the silt content was the biggest positive effecting role, followed by the negative effect of sand content and positive action of clay content. The sand and silt contentswere the main positive factors on the soil water characteristic curve shape parameter (n), but the clay content could not be ignored. For the saturated hydraulic conductivity (ks), the sand was the biggest positive factor, followed by the silt of positive factor and negative clay content, and at the same time it transferred the influence to clay content which impacted the saturated hydraulic conductivity. Sand and clay had a significanteffect to the soil water characteristic curve shape parameter n, soil saturated hydraulic conductivity was directly affected by sand (0.91) content, and the silt and clay contents influenced the soil saturated moisture content and residual moisture content (0.89). This indicated that path analysis can reveal the relative importance of various factors, through the simple causal correlationbetween independent and dependent variables.