REPORT FROM AUSTRALIA
The application of VGT has gained great momentum in Queensland, Australia in 1998, both in the applications and research fields.
The major breakthrough in VGT application here is the acceptance of VGT by the Queensland Department of Main Roads for both routine maintenance work and new roads. Following my presentation at the North Queensland Main Roads symposium in Cairns I was invited by the Department to work with the design team to incorporate VGT in the design of the upgrade of the Cooktown Development Road north of Cairns. This was the first time in Australia that VGT was incorporated into the design of a new road and specified for batter and abutment stabilisation, drainage channels and other concrete and rock structures protection. The first section of this road is now being built and 23 500 linear metres ie. 188 000 vetiver slips are needed for a short section of about 10 km of this road. Other road stabilisation works are in Mackay, Central Queensland and Toowoomba, Southern Queensland.
Mining rehabilitation has gained great momentum here, with the use of VGT to control wind erosion (dust storm) from a 300ha gold tailings dam. Mine tailings often contain heavy metals which can readily pollute the surrounding environment through both wind and water erosion. With vetivers very high levels of tolerance to soil pH and heavy metals, VGT is ideally suited for the rehabilitation of these contaminated sites.
In addition, the Regional Environmental Officer (south) of the Mine and Energy Department has also adopted VGT as the main method of stabilisation, erosion and sediment control of small mines in the region. These include gold, arsenic, and bentonite mines; clay pits and quarries.
Interest was also received from Western Australia on the application of VGT in mining rehabilitation
Three areas of research are being conducted in Queensland.
The fact that vetiver can grow in a wide range of soil conditions indicate that this species may be benefiting from symbiotic association with mycorrhizal fungi. To date, plant and soil samples have been collected at several locations and different habitats in Queensland and mycorrhizal fungi have been identified. One of the major findings to date is that both the number of species and populations of mycorrhizal in intensively cropped land are much lower in comparison to those from the poor degraded lands. This may be due to the effect of agrochemical on mycorrhizal population. The implication is that for heavily contaminated land (eg. mine tailings and landfill) mycorrhizal inoculation may be needed to ensure good and sustainable growth. Work is continuous to identify and isolate the most efficient mycorrhizal strain for inoculation purposes.
Trials are being conducted to determine the efficiency of vetiver hedges in trapping agro chemicals and nutrients in run off; sediment eroded from sugar cane fields and irrigated cotton farms.
The following chemicals and nutrients are being monitored:
Some plants have the capacity of breaking down agro chemicals under wetland conditions. A trial is being conducted firstly to determine whether vetiver has this capacity and secondly if it does, how efficient it is in comparison to other species.
TVN is one of the major sponsors of the First Asia Pacific Conference on Ground and Water Bio-Engineering for Erosion Control and Slope Stabilisation in Manila, Philippines in April 1999. Paul Truong is presenting TVN on the Organising Committee and he is also a member of the Technical Review Committee.
VGT will be well presented at the conference, with several quality papers from Australia, China, India, Philippines and Thailand. In addition Paul will also coordinate a training course and will chair a Panel Discussion on vetiver and VGT at the conference.