Effects of Soil Properties and Illumination Intensities on Matric Suction of Vegetated Soil

Abstract

Matric suction induced by evapotranspiration is an important parameter for determining the hydraulic mechanisms of vegetation on slope stability. Despite evapotranspiration closely associated with atmospheric parameters and soil conditions, the influence of soil properties and illumination intensities on matric suction of vegetated soil has so far received the least research attention. In this paper, three kinds of soil, namely, fine sandy loam, sandy silt, and silty clay, were selected as experimental soils, and Indigofera amblyantha was chosen as the test plant. The test conditions were controlled, such as the use of homogeneous soil and uniform plant growth conditions. Each specimen was exposed to identical atmospheric conditions controlled in a laboratory for monitoring matric suction responses over 10 days. The results showed that illumination intensities play an important role in evapotranspiration, and the thermal energy from lighting had a direct impact on plant transpiration, whereas the lighting only affected plant photosynthesis. Plant roots in vegetated soil can effectively improve the air intake value of soil, and matric suction induced by plant transpiration in vegetated soil was 1.5–2.0 times that of un-evapotranspirated soil. There is a correlation between matric suction and the silt and clay contents, and the matric suction of silty clay was sensitive to changes in the soil moisture content. Compared to fine sandy loam, the water retention of sandy silt and silty clay was high, and a high level of matric suction was maintained in the corresponding time. The results for predicting soil water evapotranspiration based on matric suction have theoretical and practical significance for preventing soil erosion and shallow landslides. In addition, these results have great guiding significance for agricultural production, such as irrigation.

Stability Reinforcement of Slopes Using Vegetation Considering the Existence of Soft Rock

“…Due to the catastrophic consequence caused by slope failure, many reinforcement methods have been developed, such as drainage systems [7], stabilizing piles [8], reinforcement of vegetation, among others. Due to its environmentally friendly characteristics compared to soil nails, geosynthetics, retaining structures, gabions and shotcrete, the reinforcement of vegetation, such as grass and shrubs, on the slope stability, has been gradually recognized [9][10][11][12][13][14][15][16][17][18][19][20], and there are an increasing number of slope protection engineering with vegetation grew on the slope in recent years [19][20][21][22][23][24][25][26][27][28]. In fact, vegetation-soil interaction and plant-soil-atmosphere interaction are rather complex, thus the mechanism and effectiveness of vegetation reinforcement on slope stability are significant and it has attracted much attention of researchers.…”