Crop trials show spreading frost risk could reap early sowing rewards

The key to minimising crop damage caused by frost could lie in finding the right mix of varieties, sowing times, flowering times, and improved soil conditions, according to new research and crop trials on Eyre Peninsula farms.

A group of 36 growers, advisors, researchers and industry representatives joined AIR EP’s From Frost Risk to Yield Reward crop walk at Tooligie Hill and Lock on 7 August.

The day highlighted local trial results alongside the experience of independent consultants, researchers, and growers to explore how farming systems can be shaped to better manage frost risk – while still chasing profitable rewards.

AIR EP Executive Officer Naomi Scholz said the key message was that frost management was complex, but possible, by finding the right mix of approaches for each property and paddock.

“Frost damage is a significant risk for Eyre Peninsula farms, and has the potential to cause major damage and losses,” she said.

“What our latest crop walk and trials show is that the goal shouldn’t be trying to eliminate frost risk altogether – but rather building a farming system that is less exposed to single frost events.

“It was encouraging to see that there are effective approaches for farmers to use in combination to mitigate frost risk and protect yield potential, such as matching varieties to sowing opportunities, creating genuine differences in flowering times, spreading crop and sowing-date risk, and improving soils and getting nutrition right.”

The frost trial sites demonstrated the variability of frost impacts on different landscapes. At the high-risk site, 15 frost events and 125 hours below 0°C were recorded at canopy height, compared with 11 events and 87 hours below 0°C at the medium-risk site, less than 100m away.

“A strong theme from the discussion on the day was that there is no single solution to frost,” Ms Scholz said.

Instead, it was recommended that growers spread that risk across crop types, sowing dates and crop phenology to avoid having large areas flowering simultaneously.

One option for growers is to consider winter and slower-developing cereals in a diverse crop mix.

Farmers heard that trials of the Mowhawk quick winter wheat with earlier April sowing on Eyre Peninsula had shown an ability to hold back heading while still developing early enough to avoid the worst of a hot spring. This season, Mowhawk sown around 5-10 April was at a similar growth stage in early August to Scepter or Tomahawk sown around 10-15 May — a difference of about 40-45 days. To create meaningful variation in frost exposure, growers heard they needed at least 14 days difference in maturity.

For pulse crops, the discussion highlighted the importance of paddock and soil-type selection, disease management and understanding how different crops respond to frost.

At the Yield Frontiers trial near Lock, attention shifted to how growers can use sowing time, nutrition and crop choice to push yield and profitability. The discussion identified 20 April to 5 May as a useful emergence window in the Lock area, while also recognising the challenge of dry starts and delayed emergence.

“It was clear that diversity becomes even more valuable when the season does not follow the plan,” Ms Scholz said.

Barley continues to feature strongly in this system, with discussions around early-sown Neo barley as a way to increase diversity without adding more wheat varieties. Key considerations for lifting yield and profitability around Lock included sound background nitrogen, sand amelioration, barley in high frost-risk areas, maintaining pasture in the rotation, spreading variety risk and setting realistic yield targets. A practical rule of thumb was to aim to finish sowing by mid-May, which means getting started around mid-April when conditions allow.

“This event was a great opportunity for us to share the latest outcomes of our research with growers, and to hear about what’s been working for them this season in frost risk management,” Ms Scholz said.

“We’re looking forward to seeing the outcomes of more of our trials and research next month at the Lower EP Crop Walk, and the Regenerative Ag Forum.”

The AIR EP From Frost Risk to Yield Reward project is supported through the Australian Government’s Future Drought Fund and delivered in partnership with EPAG Research, CSIRO and the Grains Research and Development Corporation (GRDC). AIR EP thanks its project partners for their contribution to the research and trials.

The AIR EP Lower EP Crop Walk will be held on 8 September. The Regenerative Ag Forum will be held on 29 September at the Ungarra Complex with a trial visit. It will cover getting the best out of farm inputs, improving nutrient efficiency and supporting beneficial insects.