THE benefits of a break from wheat in low rainfall Mallee environments has been proven in a joint Grain Research and Development Corporation (GRDC) and Mallee Sustainable Farming (MSF) crop sequencing trial.
Michael Moodie, Moodie Agronomy, spoke at last week’s Mallee Sustainable Farming forum in Red Cliffs, Victoria, on the project, which has found continuous wheat is in the lower end of gross returns in a wide range of rotations tested.
Mr Moodie said the sequencing trial, conducted on a paddock at Mildura, Victoria, showed there were definite merits in break crops.
He said there would be now further trials to assess the leading rotations in MSF’s target area - sub 350-millimetre annual rainfall zones across South Australia, Victoria and NSW.
“The aim of the project was to find out whether break crops had a fit in Mallee systems,” he said.
“Now we’ve done that, we’ll see what the best rotations are.”
Clear trend of benefits
Mr Moodie said the trial did not mean the Mallee had to throw away continuous wheat, but said it showed a break crop was definitely necessary in tired soils or in paddocks with high weed burdens.
“The major issues we have in the Mallee are brome grass, low fertility and rhizoctonia and the trial paddock had issues will all of these factors.
“In better paddocks you might get a different result, but on paddocks that are run down, a break or even two break crops is the best rotation.”
Mr Moodie said break crops that did not generate an income in the year of planting often more than made up for it in terms of adding nitrogen, reducing weed burdens and boosting water availability to the following crop.
“Of the trials, we found a two-year break phase of peas and then vetch was the best.
“The trick in practice will be getting the cash crop in the favourable year climate- and price-wise to generate those good margins, but there is a clear trend demonstrating the benefits of break crops.”
Mr Moodie said a profitable break crop would be critical to wide uptake through the low rainfall zones across the three states.
“Farmers want to generate an income each year, but there are options there.”
Mr Moodie said a break from cereal crops allowed a herbicide rotation, while brown or green manuring or a fodder crop could also be used to lower the weed seed burden by preventing weed seed set.
“Something needs to be done to lower brome grass numbers throughout the Mallee and break crops will be an important part of that.”
The next step, Mr Moodie said, will be getting an idea as to the optimum intensity of break cropping and identifying any variations in different soil types.
Gregor Heard
National grains writer for Fairfax Agricultural Media.
National grains writer for Fairfax Agricultural Media.
