Contribution of the root system of vetiver grass towards slope stabilization of the São Francisco River

Abstract

The control of soil erosion along the banks of the São Francisco River requires the use of efficient and economically viable strategies. Soil bioengineering techniques may be an alternative to the conventional methods as they provide good soil stabilization by mechanical reinforcement promoted by the roots. The objective of this study was to evaluate the contribution of the root cohesion of vetiver grass (Chrysopogon zizanioides (L.) Roberty) on slope stabilization in erosion control along the right margin of the São Francisco river. Seedlings of vetiver grass were planted in the riverbank of the Lower São Francisco located in Sergipe State, northeast Brazil, and plants were sampled after two years of growth to evaluate the effect of grass on the shear strength of the soil. The monolith and cylinder method was used to collect roots for the evaluation of Root Density (RL), Root Length Density (RLD), Root Area Ratio (RAR), Root Tensile Strength (TR), and Root Cohesion (CR). Data were submitted to analysis of variance (p < 0.05), with polynomial regression analysis. The results show that for RL, RLD, and RAR, the layers of soil at depths of 0-0.10 m had the highest values of 4.84 kg m -3 , 12.45 km m -3 , 1.66%, respectively. The mean TR was 83 MPa and CR was 528 kPa. Vetiver increases shear strength of the soil and slope stabilization. Key words: Chrysopogon zizanioides, soil reinforcement, bank erosion ResumoO controle da erosão marginal do Rio São Francisco requer estratégias eficientes e economicamente viáveis. A técnica de bioengenharia de solos pode ser uma alternativa, visto que proporciona maior estabilização do solo pelo efeito do reforço mecânico promovido pelas raízes das plantas. Esse estudo teve como objetivo avaliar a contribuição à coesão do solo da raiz do capim-vetiver (Chrysopogon zizanioides (L.) Roberty), na estabilidade do talude para controle da erosão da margem direita do Rio São Francisco. Mudas do capim-vetiver foram plantadas no talude da margem direita do Baixo São Francisco no estado de Sergipe, com amostragem das plantas realizada após dois anos do plantio, a fim de avaliar o efeito da gramínea no aumento da resistência ao cisalhamento do solo. Foram utilizadas a metodologia do monólito e o método do cilindro para coleta de raiz, visando à avaliação da Densidade Radicular (DR), Densidade do Comprimento Radicular (DCR), Razão de Raiz por Área (RAR),

Biotechnical Potential of Paspalum Submitted to Simple Superphosphate Doses and Moisture Content

“…The grass Paspalum millegrana Schrad, which occurs widely in the Americas from the USA to Brazil (SOUZA-CHIES et al, 2006;OLIVEIRA et al, 2013), fits perfectly in the characteristics demanded to improve soil resistance, as it is a specie of perennial cespitos development, with long, deep rhizomes and stems with heights of 80-120 cm (MACIEL et al, 2009). In addition to having morphological characteristics that express a lot of potential to be used in the stabilization of the slopes, because when combined with other techniques of bioengineering of soils, it can contribute potentially to the reduction of erosive processes, especially as it occurs in the right bank of the São Francisco river.…”

“…In the case of the grasses vetiver grass (Chrysopogon zizanioides (L.) Nash) has been the most studied specie, the erosion control slope (SULEIMAN et al, 2013;MACHADO et al, 2015). In this sense, the knowledge of the biotechnical potential of species in Brazil, both for the control of erosive processes of marginal slopes and for the restructuring of the biological communities residing in these places, demand investigation of their ecological and agronomic characteristics.…”

Soil bioengineering in northeastern Brazil: An Overview

“…Measures to control the erosion of river or lakes banks, whether they are large, medium, or small, must consider not only geomorphological and geotechnical factors but also social factors, such as how these areas are occupied and used by the local people (Holanda et al, 2020;Machado et al, 2015). The adequate stabilization of river margins requires a combination of civil engineering technology and soil bioengineering.…”

Development and Morphometric Characteristics of Vetiver Grass Under Different Doses of Organic Fertilizer

“…It is widely known and used due to its high performance in ecological restoration programs, as well as its effectiveness in the control and prevention of erosive processes since it presents good resistance to shear stress (TRUONG;LOCH, 2004;NG et al, 2019;ETTBEB et al, 2020). The versatility of vetiver grass use has received much interest, with emphasis on its biotechnical characteristics for use in slope stabilization works, its contribution to the increase of soil cohesion and its high adaptability to various edaphoclimatic conditions (HOLANDA et al, 2012;ARAÚJO FILHO et al, 2015;MACHADO et al, 2015;COSTA et al, 2020).…”