Root Strength Measurements of Vetiver and Ruzi Grasses

Abstract

This paper aims to study effect of roots of vegetation on the stability of soil along slopes and also soil erosion. The effects of root reinforcement depend on the morphological characteristics of the root system, the tensile strength of grass roots, and the spatial distribution of the roots in the soil. The experiments were carried out to evaluate the root tensile strength of two different grasses namely: Vetiver and Ruzi grasses, by conducting the laboratory tensile tests and field direct shear tests. For each type of grass, single root specimens were sampled and tested for their ultimate tensile strength and Young's modulus in the laboratory tests. The results of laboratory tests revealed the significant correlations between root diameter and tensile force or tensile strength and Young's modulus of Ruzi and Vetiver grasses. In addition, large scale field direct shear tests were carried out involving roots of Vetiver and Ruzi grasses to evaluate the contributions of their root systems to the soil shear strength. Vetiver roots contributed higher components of shear strength compared to Ruzi grass. However, it was found that the combination of Ruzi and Vetiver grass roots yielded much better effects than Vetiver grass alone. It can be concluded that the Vetiver grass roots help enhanced the shear strength for soil reinforcement while the short roots of Ruzi grass can help control surface soil erosion.

Root biomechanical properties of Chrysopogon zizanioides and Chrysopogon nemoralis for soil reinforcement and slope stabilisation

“…The root reinforcement of highland species obtained in the present study (4.9 kPa) was lower than that reported by Eab et al (2015) (6.8 kPa). The lowland roots in this study provided more reinforcement (4.4 kPa) to soil than those in the study of Teerawattanasuk et al (2014) (3.58 kPa) and Mickovski & Van Beek (2009) (2.7 kPa). These differences could be partially explained by the variations in soil conditions and root age among these studies and could cause the biomechanical properties and reinforcement of roots to vary (Mickovski & Van Beek, 2009).…”

Root Tensile Resistance of Selected Pennisetum Species and Shear Strength of Root-Permeated Soil

“…e relationship can be represented by both power law equation [60] and second-order polynomials [39]. e power law equation was applied since this equation represents the best fit line for the data and has been widely reported by many previous researches [18,54,61]. As shown in Figure 1, the relationship represented by the power law equation for both of the studied species was very closely presented due to the small variation in diameter of root.…”

“…A significant increase in root length and root biomass that were observed in PPl species can contribute to a higher soil-root interaction. Subsequently, a great soil-root interaction will result in higher soil reinforcement that increases the shear strength of soil slope [2,54]. Root biomass increases the preferential path for the subsurface runoff, thus improving the soil shear strength and reducing slope failure [4].…”

“…In addition, the presence of higher root tensile resistance can contribute to the increased density of grass on the slope and more resistance toward overturning [1,6]. Teerawattanasuk et al [54] also mentioned the contribution of fiber on tensile strength for the tested root which varied in different species and growing period. e influence of cellulose and lignin contents on tensile strength has been comprehensively studied by Genet et al [16] and Zhang et al [17].…”

Get Tough, Get Toxic, or Get a Bodyguard: Identifying Candidate Traits Conferring Belowground Resistance to Herbivores in Grasses

“…In leaves, toughness per density makes a greater contribution to mechanical strength than lamina thickness and tissue density combined (Onoda et al, 2011), and the same may be true for root diameter and density. In both grasses and trees, the tensile strength of roots decreases with root diameter (i.e., thinner roots are stronger) and this can be explained partly by a scaling effect commonly seen in fracture mechanics and partly by the higher cellulose concentrations observed in fine roots (Genet et al, 2005; Teerawattanasuk et al, 2014). …”