Where soils have been exposed during major earthworks for projects such as pipelines or roads, there is always a need to quickly re-establish a ground cover to minimise erosion, to reduce dust losses and to restore some form of vegetation that resembles the previous plant communities. For those projects that pass through native grasslands there are usually compliance requirements of contractors to restore a native grassland that is essentially similar to that which was previously on site. This is not an easy task as all grasslands have developed over thousands of years and their complete reproduction within a 6 month time frame is essentially impossible. But steps can be taken to commence the process of full site restoration and, if carried out correctly will ultimately end up with a similar type of grassland to the desired coverage.

The key ingredient in getting a successful result is in weed control. It is our view that the weeds that are now present on most sites, and which would not have been around thousands of years ago (such as Paterson’s Curse, Gorse, Ryegrass and Paspalum) will have a huge bearing on the success or failure of revegetation efforts. Even if the soil is being returned to the site and had no weeds present at the time of removal, there are likely to be many weeds that will emerge on the site simply because the site has been disturbed. Weeds are highly competitive with emerging native grass seedlings and need to be controlled in the early stages of establishment or poor results could occur.

• Sowing at high rates to provide more plants to compete with the weeds
• Timing the sowing so that it occurs at the optimum time for the establishment of the desired grass species
• Reducing the weed content in the soil by controlling weed growth on stockpiled soils
• Spraying weeds with suitable compounds (Pine Oil or Vinegar can work as organic options, non-selective herbicides such as Roundup can work as well) in the period between the sowing of the grass and its emergence (for many grasses more than a week will pass before germination during which time the weeds can be sprayed without adversely affecting the sown grass seeds)
• Allowing the site to grow a crop of weeds, spraying out those weeds as above, and then sowing the desired grass/grasses immediately.

The more of these practices that can be put into place for the native grass sowing, the better will be the result. We suggest that a reasonable target for restoration works to aim for is a minimum of 20 plants per square metre 6 months after sowing.

The seeding mix should include some rapid establishing grasses such as Windmill grass (Chloris truncata) and Wheat grass (Elymus scaber) along with slower establishing species such as Kangaroo grass (Themeda triandra) and Wallaby grass (Austrodanthonia spp).

If the site is highly likely to erode, or if a very rapid visual result is required, then a cover crop of a cereal like Ryecorn or Japanese Millet can be sown at 20 kg/ha along with the native grass mix. The cover crop should be mowed when it runs to seed to prevent those plants forming viable seed. These are annual grasses and will die off within a few months, but their root system will have contributed to hold the soil together and to protect the emerging native grass seedlings.

In some States contractors are able to obtain offsets for their site disturbance by paying for the ongoing management and maintenance of an existing grassland that is located nearby. The rules on this vary from State to State but essentially they are set up so that contractors can meet some of their revegetation requirements off site.