![Bengworden fine wool producer Rick Robertson, in a photo taken last year, is a saltbush advocate. Bengworden fine wool producer Rick Robertson, in a photo taken last year, is a saltbush advocate.](/images/transform/v1/crop/frm/silverstone-agfeed/679787.jpg/r0_0_300_271_w1200_h678_fmax.jpg)
RICK Robertson grazed Merino sheep on his East Gippsland property for decades, but a spate of eight dry seasons had him scrounging for a productive summer feed supplement.
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He searched for a cost-effective alternative and in doing so agreed to be one of a network of 1200 producers Australia-wide who took part in an Oldman saltbush (Atriplex nummularia) grazing trial funded by the $20 million wool industry project, Land, Water and Wool.
“We just couldn’t sustain grazing over the whole farm and kept having to buy in feed to get us through summer,” he said.
Seven years on, the decision has proved to be a master stroke for him, with the 19 hectares now planted capable of supplementary feeding 1000 Merinos through summer.
But although Mr Robertson’s success with saltbush has been emulated by a rising number of sheep producers across Australia looking for a feed supplement or to avoid land degradation, questions are being asked just how cost effective the native plant is, and how can productivity be optimised from saltbush stands?
“The use of it (saltbush) is definitely increasing in sandy country and lower rainfall areas but we don’t have the numbers or the certainty of its cost benefit to livestock,” said Productive Nutrition livestock consultant San Jolly.
Anecdotally, productivity varies across a range of different environments, so is saltbush the answer in all situations?
“Is it the most cost-effective drought reserve? We don’t know,” Ms Jolly said.
Launching a three-year project funded by the SA Sheep Industry Fund and managed by SASAG that will tackle these questions this week, Ms Jolly said the majority of producers using Oldman Saltbush were still not aware that it was unsuitable as a standalone feed for most classes of sheep and cattle.
“On paper it should be a really good feed source but if people are looking for a standalone feed it is not good, as it won’t make up more than half of the diet,” she said.
The project, beginning next month, will study the impact different feed supplements have when combined with saltbush in an attempt to identify the most cost effective and productive supplement, which may not be barley or barley straw as commonly touted.
On three trial sites in South Australia, the productivity of sheep, as well as plant dry matter production will be monitored.
Two of the sites will be non-saline (one deep sands and other clay soils), while the third site will be a saline site.
One of the trial sites will be run in collaboration with SARDI.
“It is now well recognised that high salt intake increases the energy requirements of the animal therefore it makes sense to supplement with an additional energy source such as cereal grains however responses to barley have varied widely and it is clear that there are other factors that require investigation”
She said establishment costs vary from $31 a hectare to $494/ha depending on row spacings with the median costs being around $300/ha; although the life expectancy of saltbush plantations can be up to 100 years, the cost of annual supplementation needed to be accounted for.
“There is no doubt about the environmental benefits of saltbush, however, the productivity cost benefits need to be accurately determined so that producers could make informed choices about the overall benefits of plantations.”
One aim of the project was to investigate practical solutions for producers while organisations such as CSIRO and the Future Farm Industries CRC continue their research into the effect of high salt loads on rumen microbial populations.
Saltbush’s combination of deep roots, high protein and mineral levels, green leaf and particularly high sulphur content and ability to thrive in low rainfall sandy soil has caused usage to surge in the past ten years.
Anecdotal figures suggest in a rotational grazing system which includes Oldman saltbush it will carry four times more stock per hectare in the first year of grazing use and up to six times from each year after.
Ms Jolly said researchers were keen to share their research and to encourage discussion and input at field days, workshops and via newsletters.
* Visit www.productivenutrition.com.au