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),