Therese McBeath 1, Vadakattu Gupta 1, Rick Llewellyn 1, Bill Davoren 1, James Hunt 1, Roger Lawes 1, Claire Browne 2, De-Anne Ferrier 2 and Michael Moodie 3
1 CSIRO, 2 Birchip Cropping Group (BCG) and 3 Mallee Sustainable Farming (MSF)
Presented at the GRDC Grower Updates, 23rd July 2014, Speed, Victoria
Take home messages
• Combined analysis of trials hosted by BCG and MSF show that first year effects of legumes are generally more reliable than oilseeds for improving subsequent wheat yield.
• Increased nitrogen supply could be measured up to two years following the break and played a key role in the break effects at Karoonda and Hopetoun where weed burden was low.
• Disease breaks tended to only last for one wheat growing season.
• Sites with a high grass weed burden require a two year break to reduce the weed seed bank to a level that enables consistent improvements in cereal production.
• Measuring the gross margin of production over a three-four year period showed that the inclusion of legume and canola breaks in the sequence was at least as profitable as continuous wheat.
• Two year breaks can increase the variability in gross margins in the years breaks are implemented but significant profit gains compared to continuous wheat were made at both sites for a small selection of treatments.