Vetiver grass mulch for prevention of runoff and soil loss

Vetiver grass is used for reducing soil erosion and has been applied in many areas around the world. However, few studies have been carried out using vetiver grass mulch (VGM) for soil erosion control. The performance of VGM in soil and water conservation is investigated by determining the effects of a quantity of VGM on the prevention of runoff and soil loss. The study involved field experiments with a land slope of 3%. Two rainfall intensities of 55 and 140 mm/h were selected because these cover the rainfall intensity in the Upper Thachin watershed in Thailand at a 1 hour in 2 years and 500 years recurrence interval. Six dry matter quantities of VGM were used in the study: 0·25, 0·50, 0·75, 1·0, 1·5 and 2·0 kg/m². The runoff volume decreases with the increase in the quantity of VGM, with values ranging from 5·6 to 46·1 mm. The VGM showed good potential for reducing runoff and soil loss by 33–71% and 31–82%, respectively, when compared with the position without VGM. The higher quantities of VGM can reduce soil loss more than the lower ones. VGM at 0·75 kg/m² is found to be a suitable quantity for reduced runoff and soil loss.