Effect of Vetiver Roots on Soil Resistance to Penetration in a Typic Fluvic Neossol in the São Francisco Riverbank

Abstract

The aim of this study was to evaluate the effect of the root of vetiver grass (Chrysopogon zizanioides (L.) Robert) on the soil Resistance to penetration (RP) in the margins of the lower São Francisco River. Vetiver grass seedlings were planted on the riverbank margins in order to increase soil resistance to erosion processes, and RP assessments were made at soil depths of 0-0.20, 0.20-0.40, and 0.40-0.60 m in different situations (near the plants and within rows). RP data was obtained using an automated penetrometer. Gravimetric moisture data was also collected, as well as particle size data by densimetry, and root density data by the monolith method. The results of the RP, moisture, and root density studies were subjected to analysis of variance (p <0.05) and then the averages were compared by the Tukey test using SISVAR software. The samples next to the vetiver grass showed an average RP of 1793.94 kPa and an average moisture content of 11.78%, statistically differing from that of the sampled points within rows. RP and soil moisture did not differ statistically at the depth assessed. The vetiver grass produced an adequate ground cover, leading to higher water retention and hence a reduced resistance to penetration.

Soil bioengineering in northeastern Brazil: An Overview

“…The biotechnical potential of Vetiver grass and Paspalum grass species lies in the resilience of its roots against the forces of traction and cutting, its resistance to strong mechanical stress, and its ability to create a structured soil by increasing the capillarity and permeability (Islam and Shahin, 2013;Mickovski and van Beek, 2009). According to Machado et al (2018) the mean Root Tensile Strength (TR) of 83 MPA was obtained during testing of the Vetiver grass. However, the variability in TR may occur due to root age, growth rate, and growth orientation by changes in the soil moisture content, and soil texture, as was also stated by De Baets et al (2008).…”

“…These techniques use a mixture of inert materials, such as rocks, wood, natural fiber (geotextile) or synthetic photodegradable geotextile, with biological materials, such as shrubs or poaceae seedlings, as well as plant cuttings, seeds etc. In the design of structures for protecting the river banks from erosion, it is important to combine living and inert elements (Holanda et al, 2017;Machado et al, 2018). Geotextiles have been demonstrated to help stabilize slopes and to efficiently control bank erosion (Araújo-Filho et al, 2013;Holanda et al, 2009a;Ribeiro et al, 2011).…”

Relationship Between Physical and Chemical Properties of Entisols-Fluvents and Erosion in the São Francisco River

“…Although expected, these changes interfere with the natural dynamics of the river, which may be resumed by adjusting the morphology of its channel (ROCHA et al, 2020). Such a situation can be enhanced or not by suppression of riparian vegetation (gallery forest) and constitutes a serious environmental degradation (HOLANDA et al, 2020b), given the exposure of unstable river embankments composed of lowcohesion soils (MACHADO et al, 2018).…”

Macrophytes communities associated to soil bioengineering techniques for erosion control in riverbanks

“…Another consequence is the instability of the soil aggregates after vegetation removal, which contributes to erosive processes (Machado et al 2018;Oliveira et al 2009). In order to mitigate the damage caused by erosion, scientists have developed engineering techniques combined with ecological knowledge on plant species that contribute to the roots mechanical reinforcement for erosion control (Holanda et al, 2007;Holanda et al, 2009;Araújo-Filho et al 2017).…”

“…In order to mitigate the damage caused by erosion, scientists have developed engineering techniques combined with ecological knowledge on plant species that contribute to the roots mechanical reinforcement for erosion control (Holanda et al, 2007;Holanda et al, 2009;Araújo-Filho et al 2017). Costa et al (2020) stated the importance of vegetation in the riverbanks erosion control, and also Machado et al (2018) showed in their work the importance of knowing the species morphological characteristics, in order to enable positive performance in slope stabilization. This shows that soil bioengineering techniques favor erosion control and increased biodiversity related to aquatic plant species.…”