土壤水分对植物根-土界面相互作用特性的影响

为研究不同土壤水分下不同植物根系与土壤界面的摩阻特性,使用直剪仪对内蒙古中西部的5种典型乡土植物(柠条、沙棘、杨柴、紫花苜蓿和沙打旺)的根系在不同土壤含水率下进行根-土界面直剪摩擦试验。结果表明:当土壤含水率在4.5%~24.5%时,5种植物根-土界面摩擦系数均大于素土的土-土界面的值,且随着土壤含水率的增加,根-土界面和土-土界面摩擦系数均呈下降趋势,其中沙棘根-土界面的摩擦系数和黏聚力均大于其他4种植物的值,表明仅从根系与土壤间的相互作用特性来看,沙棘根系固土抗蚀的作用明显优于其他4种植物。根-土界面和土-土界面黏聚力均随着土壤含水率的增加呈先增后减的变化特征,且植物种不同黏聚力峰值出现时对应的土壤含水率亦不同。

Effect of Soil Moisture on the Characteristics of Root-soil Interface Interaction

In this study, we used the direct shear apparatus to study the direct shear friction characteristics of root- soil interface under different soil moisture content in the Midwest of Inner Mongolia. Five kinds of typical local plant, including Caragana Korshinskii, Hippophae rhamnoides, Hedysarum fruticosum, Medicago sativa and Astragalus adsurgens, were selected as experiment plants. The results showed that friction coefficients of root-soil interface for the five plants were all higher than those of soil - soil interface when soil moisture content varied between 4.5% and 24.5%. And friction coefficients of root-soil interface and soil-soil interface both decreased with the increasing of soil moisture content. The friction coefficient of root-soil interface and cohesion of Hippophae rhamnoides were both greater than those of other four plants, and this indicated that the effect of Hippophae rhamnoides roots on soil erosion resistance was greater than the other four plants according to the interaction between root system and soil. The cohesions of root-soil interface and soil-soil interface all increased first and then decreased with the increasing of soil moisture content. For different plant species, the soil moisture content was different when the cohesion peak appeared.