Contribution of root tensile of Pennisetum polystachion on shear strength of sandy soil in slope bio-engineering technique

Abstract

Aim: In soil bio-engineering, plant has been widely adopted as important material in promoting sustainable ecological function in slope instability measures. Plant canopy provides shelter and at subsurface level, root networking attributes toward stability of soil against erosion and slope failure. To investigate the potential of selected P. polystachion as biological material in soil bio-engineering for improving the soil shear strength of sandy soil planted with P. polystachion. Methodology: The selected species was initially planted using hyroseeding technique on studied plots which facilated with and without fiber netting (made of paddy straw). A control plot was also prepared for reference of this study. The plots were routinely watered twice a day for six months before experimental program was scheduled for determining of root tensile and soil shear strength tests. Results: The root tensile strength of P. polystachion exhibited a positive significant relationship between root tensile force and root diameter. The shear strength of soil was affected by the presence of root if compared to that of soil without root (control). Biomass analysist also agree with the soil water content, ws. High biomass contributed to the increase in the values of soil shear strength parameter of cohesive, c and angle of friction, q for root-permeated soil with P. polystachion. Interpretation: This study has suggested that the potential application of this selected species for slope vegetation in improving the erosion control and slope stability in soil-bioengineering scheme.