Managing the composition of native and naturalised pastures with grazing

Many native, naturalised, and low-input pastures have a low proportion of desirable species. Under the prevailing economic conditions, it is unlikely that these pastures would be replaced with sown native species as there may not be seed of suitable cultivars available and costs would exceed returns. Better management is a preferable strategy to improve the proportion of desirable components. Grazing tactics are central to any improved management strategies for these pastures as they offer a lower cost option for land managers. Additional tactics, which will vary depending upon specific circumstances, include some use of fertiliser (to increase the rate of change), herbicides (where weed problems are particularly severe and animals are unlikely to eat the “weeds"), and fire (to reduce dead material and seed numbers and produce green leaf for grazing). Several examples of manipulating pasture composition are considered. In situations where the desirable species are C3 perennial grasses (e.g., Danthonia spp., Microlaena, and Dactylis), and the less desirable are C3 annual species (e.g., Vulpia), rests over the summer period, especially in wetter years, improved the perennial grass content. In addition, extra grazing pressure in spring limits seed set by annual grasses. Where the undesirable species are C4 perennial grasses (e.g., Bothriochloa and Aristida), heavy summer grazing is more important. In some instances, the timing of a heavy grazing period will depend upon monitoring the plant community to find the “window of opportunity” when the desirable species have completed flowering and seed set but when the less-desirable species are starting to flower. Further development of improved management systems will require knowledge of the ecology of the principal species. Any release of new cultivars of native and low-input species should be supported by knowledge of the better management practices to maintain those species in the pasture.