Research into regenerating irrigated land has been the focus of the Economically Viable Options for Retired Irrigation Land (EVORIL) trial involving landholders and industry specialists in the Swan Hill district.
Beginning in 2013 with four sites of between eight and 40 hectares, it was expanded in 2016 to include an additional four 20 hectare sites which were further divided into five ha plots.
Those small plots contained a mix of productive and resilient species identified during the initial pasture trials, with the aim of conducting the EVORIL grazing trials to assess weight gain and recommended stocking density in the new pasture systems.
Central Murray Bestwool Bestlamb Group, Project Officer, Rick Ellis, said 40 different species are being evaluated in the small plots before moving onto bigger sites in the 250-325mm rainfall country in southern NSW and northern Victoria.
“This project has been designed to allow people to interpret data in relation to their own enterprise aims,” Mr Ellis said.
“We don’t believe that a single pasture mix will suit all property management practices.”
Mr Ellis admits there is a lot to learn about many of the species and how they can be grazed for best performance.
“The most promising trial species produce aerial seeds and they can be prone to overgrazing,” he pointed out.
“These species must be treated in the same way as a [grain] crop in the establishment year to encourage maximum seed set.”
Project coordinator Rick Ellis said that would mean minimal grazing as it is most important to remove stock prior to flowering to allow plants to set the maximum number of seed pods.
“Despite the best grazing management and seasons, some species will not be very prolific the year after planting due to ‘hard seeded’ characteristics,” he said.
“This is a long-term advantage, as one the the seed bank is established, a poor season or opportunity cropping will only have a small effect on the profligacy of the pasture species.”
Each trial site has side-by-side plots planted with a combination of saltbush and pasture (medics, lucerne, ryegrass, fescues) grazing May/June 2017 drop ewe weaners not yet classed.
Five mobs of sheep were put into the plots on 9 January, then taken out and weighed on 24 January.
They showed an average weight gain of five kg for the 15 day period while the control plot had a daily weight gain (dwg) of 316 grams and the saltbush/pasture plots 475 gram dwg.
Palatabilty test varied, with the plot with Narromine sourced saltbush was all eaten as opposed to the WA saltbush variety.
If there is one message about establishing pastures on retired irrigation land is that it is not a one year 'sow and forget' proposition
Grazing performance on western pastures
Landholders involved in the Economically Viable Options for Retired Irrigation Land (EVORIL) trial include David and Simon Ettershank, "Murray View", Murrabit.
They are one of eight producer demonstration sites across the Murray river shire involved in the Central Murray Bestwool Bestlamb Group / Western Murray Land Improvement Group Inc project looking at making country more productive with increased weed control in areas with low irrigation water availability.
Grazing trials began early this year on “Murray View”, where 2,700 Merino ewes are grazed on the 2,000ha property.
Simon Ettershank said they were interested, like other landholders, in the EVORIL program for the opportunity to lift production on their irrigated paddocks during periods of low water allocation.
Saltbush was grown from seed collected from the western Murray district and direct drilled into existing pasture on “Murray View”.
Rick Ellis noted the saltbush was planted at a density of 540 plants/ha with an inter-row pasture to provide energy and fibre with the high protein saltbush.
“If there is one message about establishing pastures on retired irrigation land is that it is not a one year ‘sow and forget’ proposition,” he said.
Western Murray Land Improvement Group Inc, Regional Landcare Officer, Roger Knight noted grazing data varies between plots, but current research results are encouraging.
“Obviously there are large differences in grazing performance based on the class and or age of sheep,” he said.
“Grazing for the trial was done over 25 days with a view to conserving ground cover, and it was recognised that labour intensive slashing and cell grazing is not practical, nor practiced in many cases.”