NATIVE Oldman saltbush (Atriplex nummularia) is a common sight in Australia’s arid regions, with a reputation as a hardy shrub and reliable forage for grazing livestock.
CSIRO-led research has now put new life into Oldman saltbush, with a recently released elite variety called AnamekaTM showing quantified improvements to farm profitability and ecosystem health.
Over 60,000 Oldman saltbush plants were tested to identify individual plants with the highest feeding value. AnamekaTM was the best of those plants, and it was successfully released commercially in 2015, with the sale of more than 1.5 million plants in only four years. About one million seedlings are expected to be sold in 2019.
CSIRO researcher Dr Hayley Norman says findings have shown the saltbush variety can have far-reaching benefits for farmers who adopt the plant as a forage for sheep and cattle. But in a world where money talks, the headline benefits are economic.
“While AnamekaTM has been selected for higher energy values and relative palatability, these long-lived woody shrubs offer a lot of additional incremental benefits that add up,” Norman says.
“Additional benefits include reduced recharge of water tables in areas at risk of salinity and ecosystem services. But it’s plugging the annual feed gap – which is largest during lean years – that provides single biggest economic benefit.”
Ten years of research with sheep in farmers’ paddocks has found that sheep with access to the optimal variety of saltbush grew 20-25 per cent more wool compared to those feeding on hay, crop stubble or pastures alone.
For meat production systems, foraging on saltbush also helps sheep to maintain vitamin E levels over summer and autumn, leading to healthier sheep, possible improvements in reproductive efficiency and meat with a longer shelf life.
It’s not just vitamin E either. Recent work demonstrates the shrubs accumulate minerals associated with antioxidant pathways, including selenium, copper, manganese, zinc and sulphur.
Findings also show that planting saltbush improves biodiversity and environmental sustainability.
A recent project – supported by Australian Wool Innovation and the Australian Government Department of Agriculture and Water Resources – showed substantial cost savings by reducing the amount of money farmers need to spend on supplementary feeds.
“During autumn there is an on-farm feed gap that occurs after crop harvest and when there is low rainfall in many parts of southern Australia. We’ve seen exactly that during the current drought,” Norman says.
“Allowing sheep to graze on high-performing shrubs that require low ongoing costs after planting is a big money saver for farms.”
The sheep also need little convincing to flock to the saltbush shrubs. One trait the researchers were looking for when they initially tested the 60,000 plants was relative palatability.
“Sheep are actually quite fussy eaters, and we saw stark differences between some shrubs being picked bare and others left practically untouched,” Norman says.
“However, not only are they very keen on it, it’s also a great complement to poor quality summer and autumn diets. The saltbush acts as an energy, protein, sulphur, vitamin and mineral supplement.”
A farm study showed that sheep feeding on saltbush lost up to three times less weight than sheep grazing on annual senesced pastures with a lupin supplement.
Norman says saltbush also has the advantage of growing on soils that are marginal for cropping and it provides a feed buffer that allows more sheep with less risk.
That assertion is supported by Tony York, President of the Western Australian Farmers Federation and an early adopter of saltbush – so much so that the AnamekaTM variety is named after the 17,000 hectare property he runs with his family and brother Simon in Tammin – around 180km east of Perth.
He says the shrub has improved the viability of his farm, which runs as a mixed crop-livestock operation with 5,500 sheep.
“Sheep contribute around 40 per cent of our profit, but less than a quarter of our income. They’re that productive and cheap to run,” York says.
“We’ve built up our sheep operation in conjunction with increasing the number of saltbush shrubs planted on the property. It’s been a vital part of our success.”
Unsurprisingly, saltbush garners its name from its preference for growing in saline conditions, and around 4,000 hectares of Tony York’s property was too salty for growing crops.
“Thirty five years ago, when we started farming, those salty areas had nothing on them. Nothing would grow there, apart from saltbush,” he says.
“We’re now establishing AnamekaTM on salt plots and hope to get another level of production benefit. It seems to be a better feed than past varieties, and sheep graze it as a first preference.”
Norman says dryland salinity is regularly caused by high water tables, pushing salt towards the surface. Fortunately, work with the Western Australian Department of Primary Industries and Regional Development and CSIRO hydrologists has shown that planting saltbush has another benefit which can transform the soil profile.
“Saltbush lowers the water table by using summer rainfall, and over time salt is washed back down the soil profile and below the root zone of annual plants. This has positive flow-on effects for productivity and the environment by reducing salt runoff into freshwater catchments,” she says.
Climate change predictions for southwestern Australia indicate changing patterns in rainfall. York says that his property has been hit with long term declines in rainfall, which would ordinarily put significant pressure on his livestock operation, but saltbush has added a fall-back position for sustaining his flock.
“Saltbush grows well – even with little rain. So in the years when we’ve really suffered from lack of rain, we’ve still had adequate forage for the sheep and allowed them to maintain their condition,” he says.
“Aside from providing good feed, the shrubs also provide some shade for sheep. With long term projections showing increased temperatures and further declines in rainfall, saltbush has now become integral part of the whole farm production system.”