Demonstrating the benefits of break crops in Northern Mallee no-till cropping systems

Michael Moodie and Todd McDonald
Mallee Sustainable Farming

Why was the project was done?
Agronomic constraints threaten the sustainability of intensive cereal no-till cropping systems. Local research has shown these constraints can be managed by diversifying rotations with break crops, however as this research was conducted at only one site, farmers wanted to know whether the same results would be observed on a commercial scale at a whole of paddock level. In 2014, the Mallee Catchment Management Authority (Mallee CMA) funded a project to compare the impact and profitability of the inclusion of broadleaved break crops in paddock rotations in the Northern Victorian Mallee.

How was the project was done?
Five paired paddocks where farmers are comparing rotations that include broadleaved break crop options to cereal intensive cropping systems were first implemented in 2014. The paired demonstration paddocks are of a commercial scale and are managed by the participating farmers using commercial equipment. Monitoring is focusing on two soil types (light and heavy) within each paddock to collect data on weed dynamics, soil fertility and nitrogen (N), disease, soil water and productivity. The economics of each rotation is being compared using gross margins developed in consultation with the collaborating farmers.

Key Messages
• Broadleaved break crops increased pre sowing soil nitrogen by up to 40 kg/ha in 2014 while Rhizoctonia inoculum was also significantly reduced following these crops.
• Growing a legume break crop in 2014 increased the grain yield of the subsequent wheat crop by 0.6 – 0.7 t/ha.
• Wheat crops following legumes were twice as profitable than following another cereal crop in 2015.
• The profitability of paddock rotations that included legume break crops in 2014 were similar to or exceeded the profitability of the cereal intensive rotation in the same paddock.