Break crop adoption in the Mallee
When the crop sequencing project started in 2011, less than five percent of Mallee cropping land was sown to break crops, with intensive cereal cropping dominant in the region.
Mallee Sustainable Farming’s Michael Moodie says five years ago, there might have been “the odd paddock of canola”.
“The crop sequencing project has really changed perspectives, especially in the northern Mallee. The trials have given confidence to growers of the long-term profitability of break crops. They can rely on the four years of regionally specific data from the project to show the benefit, reducing the risk they have to take on,” Mr Moodie said.
The MSF trial, located in Mildura, trialled nine different break options in 2011, as well as a baseline wheat. In 2012 the break was either continued for a second year, or sown back to wheat. Wheat was grown on all plots in 2013 and 2014.
The site experienced below average growing season rainfall in 2011 and 2012 (108mm and 92mm respectively compared to a long-term average of 173mm), and average rainfall in 2013 and 2014.
A one-year break of field peas led to an increase of 0.3t/ha in the subsequent wheat crop, or 0.1t/ha for a canola break. However these benefits only lasted one year. After a two-year break, wheat yields increased by 0.5-1.25t/ha, with a benefit of up to 0.4t/ha observed in the second year of wheat.
The key driver for improved performance was brome grass reduction, which accounted for 39 percent of the total increase in yield in 2013 and 80 percent in 2014. Increased nitrogen, at 38 percent and 18 percent in 2013 and 2014, and less rhizoctonia at 19 percent in 2013 were the other significant causes of improved wheat performance.
In terms of profitability, 15 of the 19 rotations were more profitable than continuous wheat. On average, the top five rotations increased profit by $90/ha per year. Four out of the five top performers included a two-year break.
As a result of the project findings, growers in the Mallee are starting to embrace break crops.
“Coming from a situation where there was over 95 percent cereals five years ago, now there’s wide ranging plantings of field peas, and vetch – for manuring or livestock. Here and there you can see chickpeas, lentils, and lupins. Growers are really expanding their horizons, using a wider range of crops in their farming system which, as the trials show, is a really positive move not only for soil health and weed control but also profitability,” Mr Moodie said.
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GRDC Project Code DAS00119