THE ROLE AND FUTURE USE OF PERENNIAL NATIVE GRASSES FOR TEMPERATE PASTURES IN AUSTRALIA

Increasingly in Australia there is evidence of pasture decline; acidif ication, salinisation, and land degradation are all indications that p astoral and landform ecosystems are not in equilibrium. With declining terms of trade for farmers, rapidly increasing costs of pasture estab lishment and maintenance, and an increased environmental awareness in the community, it is timely to consider the future and role of perenni al native grasses in temperate pastures. Undoubtedly the sowing of per sistent, well-adapted, deep-rooted native or introduced grasses can re duce the rate of acidification or salinisation. Native grasses evolved under conditions of a mostly dry and fluctuating climate, low nitroge n and phosphorus soils, low grazing pressure by soft-footed marsupial herbivores, low trampling pressure, high summer fire frequency, and lo w densities of legumes such as Swainsona, Lotus, and Glycine. While in troduced temperate perennial grasses often require a companion legume and fertiliser input for productivity and persistence, the adaptive ch aracteristics of some native grasses may be useful, particularly in ma rginal environments where sown perennial grasses have poor persistence . In many districts, all native grasses were thought to have similar a daptive characters and so a philosophy evolved among many agricultural ists to replace indigenous plants with fertilised legume-based pasture s. This assumed that the level of land capability could be permanently increased by adding introduced species to the pasture ecosystem, but there is increasing evidence that this may not be so. Where useful nat ive grasses predominate, they have a continuing role as a major pastur e resource on most properties. Some farmers on the Tablelands of New S outh Wales have developed stable and productive native grass-based pas tures, carrying 8-15 dry sheep equivalents/ha, by manipulating grazing pressure, fertiliser use, and legume growth. In winter rainfall and c ropping zones, such as the Riverina of New South Wales and the Mallee districts of Victoria, where native pastures occupy less than 25% of t he agricultural land, native grasses are under test, because it is tho ught they are more likely than introduced species to have a restorativ e role in acidified, salinised, or degraded cropping lands. The availa bility of seed of the better native grasses by domestication and seed harvesting is seen as an adjunct to these roles, and not as providing replacements for other persistent, productive perennial grasses.