Farm Table says:
What is the problem?
This paper compares the seasonal dry matter production and WUE of pastures commonly sown in the perennial pasture zone of southern Australia with three pasture mixes where lucerne is substituted for subterranean clover. We test the hypothesis that lucerne mixtures contribute a greater supply of feed for a limited supply of water than other commonly used pasture types at the times of highest value to a meat-sheep enterprise and without the weed and soil N build-up problems of pure lucerne.
What did the research involve?
The experiment was conducted at the Department of Economic Development, Jobs, Transport and Resources research farm, Hamilton, Victoria, Australia. The site has a temperate climate with winter–springdominant rainfall, an average annual rainfall of 681 mm, and a mean daily temperature range of 11268C in the warmest month (February) and 4128C in the coolest month (July). The soil was a Brown Chromosol derived from basalt and consisted of a mildly acid clay loam topsoil with a gravelly buckshot layer at its base, overlying a heavy clay subsoil. The site was on a gentle ridge and was well drained.
What were the key findings?
In the second year, dry matter production from lucerne mixtures exceeded that of equivalent mixtures with subterranean clover in spring, summer, and winter. In spring, the Lucerne component continued producing for longer than the clover component through its use of deeper stored soil water, and in summer, lucerne continued to grow slowly after the grass component had entered a drought-induced dormancy. In winter, the contribution from the Lucerne component complemented, rather than competed with, that from the non-legume component. Water-use efficiencies during winter-spring ranged from 4 kg ha–1 mm–1 for chicory–clover to 27 kg ha–1 mm–1 for a fescue–lucerne mixture, and during summer-autumn from nil for cocksfoot–clover to 13 kg ha–1 mm–1 for a fescue–lucerne mixture.
Data from the second year of this experiment clearly support the hypothesis that grass–lucerne mixtures contribute a greater supply of feed for a limited supply of water at certain times of the year than equivalent mixtures with subterranean clover or other commonly used pasture types. The grass–lucerne mixtures provided a greater feed supply in late spring, summer and the following winter. In each of these seasons, different mechanisms were responsible for the additional forage growth.