Growers and advisors at the Grains Research Development Corporation (GRDC) Research Update in Corowa this February will hear the latest in local research on retaining stubble.

Riverine Plains Inc is a grower group dedicated to improving the productivity of broadacre farming systems in north-east Victoria and southern New South Wales. The group is one of 16 farming systems and research organisations involved in GRDC’s flagship stubble investment, ‘Maintaining profitable farming systems with retained stubble.’

The investment, which finishes in June 2018, is driving exploration of issues that impact the profitability of retaining stubbles across a range of environments in southern Australia. The aim is to develop regional guidelines and recommendations that assist growers and advisers to consistently retain stubbles profitably.

Riverine Plains Research and Extension Officer Dr Cassandra Schefe said the group established four large, commercial scale field trials at Dookie, Yarrawonga, Henty and Coreen/Corowa (‘Focus Farms’).

“These trial sites compared different stubble management practices and plant establishment, growth and yield,” Dr Schefe said.

“Smaller trials also evaluated the importance of timing of nitrogen (N) application, plant growth regulators, row spacing and variety selection in optimising production in stubble retained systems.

“The large plot field trials were always placed into a cereal stubble, so the sites didn’t continue in the same location every year, but were placed in different paddocks to maintain the same rotation position, with the trial crop being sown into wheat stubble.”

Dr Schefe said while the trial results cannot be directly compared across seasons (2014 to 2017), the effect of different stubble management techniques can be reviewed across years to determine if any single approach appears to consistently yield better.

“Generally, across the past four seasons stubble management has not been a key driver of yield, except for stubble height at Dookie, and addition of N at sowing at Yarrawonga and Henty in 2014,” she said.

“This general lack of effect may be largely due to extreme weather through some of the growing seasons, being heat stress in October 2015, and waterlogging and high cloud cover in winter and spring 2016, which would have overridden any effects of stubble management on yields.

“The timing of flowering had a strong impact on the degree to which these two factors influenced final crop yields”

A key Riverine Plains Inc project finding is that stubble management can directly influence flowering date, which Dr Schefe said may be of value as a risk management strategy to spread the risk of frost damage or water stress in a dry spring.

“This finding is dependent on other factors though, with the high frequency of frosts in 2017 meaning that frost damage was likely to occur over a range of flowering dates.

“The impact of stubble management has certainly differed according to site and season over the past four years.

“It is important to view these results within the context of the seasonal conditions. Therefore, the most productive and profitable approach to stubble management may change according to the season.”

Dr Cassandra Schefe will address the one-day GRDC Research Update at Corowa on Thursday 15 February 2018. Other speakers include Roger Lawes from CSIRO on Understanding the basis behind the yield gap and Rohan Brill from NSW Department of Primary Industries on Critical Agronomy management points for optimising canola profitability.

Go to www.grdc.com.au/events/list/2017/02/grdc-grains-research-update-corowa for the full list of speakers and to register.