Soil Binding Capacity of Different Forage Grasses in Terms of Root Reinforcement Ability toward Soil Slope Stabilization

Abstract

The use of vegetation in restoring the stability of slopes becomes highly demanded especially to solve the soil of erosion, shallow slope failure in both natural and man-made slopes. Planting or preserving vegetation in areas vulnerable to erosion is therefore considered to be a very effective soil erosion control measure. The above-ground biomass can temporally disappear in semi-arid environments, roots may still be present underground and play an important role in protecting the topsoil from being eroded. The load required to remove the root system of each grass vertically from the soil was used as a measure of soil binding capacity. We have observed maximum and minimum uprooting force for TSH (179.75 kg) and Chrysopogon fulvus (85.33kg), respectively. We found highest "soil binding strength index" for Heteropogon contortus (5.32) and lowest in Cenchrus ciliaris (3.44). The grass, which is having maximum value of Cr will have maximum soil binding capacity. The additional shear strength imposed by the grass roots was observed maximum for H. contortus (365.0 kPa) and minimum was observed for C. ciliaris (139.3 kPa). Root systems lead to an increase in soil strength through an increase in cohesion brought about by their binding action in the fiber/soil composite. From this study, it has proven that grasses are effective for erosion control, providing a complete ground cover and grass roots have a mechanical effect in increasing soil strength. The calculated cohesion values are used to rank species according to their potential to reinforce the soil.