Comparison of secale with other perennial grasses under grazing at a cool site in the high rainfall zone of New South Wales

Abstract

Summary. In 2 field experiments on the southern highlands of New South Wales, the short-lived perennial grass secale (Secale montanum Guss. cv. Black Mountain) was grazed by Merino wether weaners at stocking rates of 10–17 animals/ha to test the suggestion that persistence might be enhanced by occasional deferment of grazing to encourage seedling germination.

In the first of these experiments (experiment 1), designed to compare secale and phalaris, when accompanied by white and subterranean clovers, growth and survival of both grasses was poor, despite the application of >600 kg/ha superphosphate and the experiment was abandoned after 2 years. A subsequent pot trial (experiment 2) with secale grown in soil from the experimental site, where the fertiliser had been applied, showed a large growth response to additional phosphorus.

Because inadequate soil fertility may have been the cause of poor grass persistence in experiment 1, a second field experiment (experiment 3) was established on the same site to compare secale, perennial ryegrass and cocksfoot, each accompanied by white and subterranean clovers and with the application of a further 850 kg/ha superphosphate over 3 years. Initial growth of all the grasses was good and animal production on the secale and ryegrass plots was high (up to 100 kg/ha greasy wool and 300 kg/ha liveweight gain). Secale failed to survive more than 3 years, despite deferment of grazing and it may be that persistence depends more on the reliability of autumn rainfall. However, mean weight gain from the clovers and volunteer grasses on the secale plots in the fourth year was as high as from the ryegrass plots and double that from the cocksfoot plots, which became increasingly cocksfoot-dominant.

While the results indicate a need for more work on the fertiliser requirements of perennial grasses on these soils, they also raise questions about whether these grasses benefit animal production sufficiently to justify the cost of establishing them.