Effectiveness of Vetiver Grass in Erosion and Sediment Control at a Bentonite Mine

In Australia, the mining industry is much concerned about how mining practices can affect the wider community and environment. One particular aspect of this is the mining operation’s treatment of waste and runoff water before it runs from the mining ground. Waste materials from bentonite mining can be highly sodic and infertile, as they often have high Montmorillonite clay content. These materials are highly erodible due to the highly dispersive characteristics of the sodic soil when wet. High water velocity, particularly from concentrated flows of runoff water, will lead to severe erosion problems on these soils. Sodium also provides unfavourable conditions for ground cover establishment. Field trials were conducted to determine the establishment of vetiver grass on very high exchangeable sodium soils and the effectiveness of vetiver hedges in spreading concentrated flows and trapping sediment over major flow areas, in providing a support mechanism for other plant growth and in reducing signs of visible erosion. Results to date have shown that vetiver hedges will establish easily on extremely sodic soils when adequately supplied with fertilizers and water. Although not fully established (10 months old) the hedges are very effective in trapping both coarse and fine sediment (which will support other plant life) and have reduced visible signs of erosion