construction and refurbishment of earthen irrigation channel banks

17.7.2 Rope Wick ApplicationMuch of the topsoil used in Northern Victoria and southern New South Wales forcovering channel banks contains some Couch and other creeping plant species.However these are often overtaken by Phlaris and other high-growing vegetationwhich are not as desirable as the prostrate species. To encourage growth of theprostrate species a rope wick applicator can be utilised. This consists of a ropewick attached to a boom filled with herbicide in front of a tractor. The boom can behydraulically lifted to suit the application. The boom can be set at a level to wipethe high growth with glyphosate while missing the low-growing species.The Rope Wick Application is a relatively cheap method of establishing vegetationgrowth although its limitations are that it requires specialist equipment and is onlysuitable to promote vegetation growth if the desirable species are already containedin the topsoil.17.7.3 Vegetative PropagationVegetative propagation is the harvesting and re-planting of vegetative material toestablish vegetation growth on an earthen channel bank.This procedure has been used by Murray Irrigation in establishing Common Kikuyualong their earthen channel banks.Kikuyu runners were harvested by hand from where it was established on otherchannel banks. These pieces of material were then planted at 1 metre intervalsalong the crest of newly constructed banks. With sufficient rainfall many of thesebanks had a complete coverage of kikuyu across the crest within two years.Photos\protective cover\grassychannel.jpgPhoto 17-3Kikuyu on channel banks constructed 4 years previously.Establishing vegetation on channel banks from runners or cuttings is the preferredmethod to avoid seed being blown into neighbouring pasture and crops. However ithas the disadvantages of being labour-intensive and therefore costly.17.7.4 Sowing SeedSeeding with a broadcast mixture of hardy grasses, adapted to the soils and climateof the area, is reasonably effective if done early in the growing season. The seed isapplied in the specified quantities and distributed uniformly over the area. Topsoilis important in providing a suitable seed bed and encouraging even germination.Germination and establishment are also significantly improved by using fertiliser.The flatter and rougher the batter slope, the better the retention and germinationrate.Seed can be sown by hand, normal agricultural equipment in drills or byhydromulching. The advantages and disadvantages of these two methods are listedin Table 17-3.Construction and Refurbishment of Earthen Channel Banks August 2002 – Edition 1.0 17-11