Australia
March 20, 2014
Grain growers can best minimise crop losses from spring frosts by planning and implementing strategies prior to or at seeding time.
This was the message delivered by ConsultAg director Garren Knell to Western Australian growers at a series of Grains Research and Development Corporation (GRDC) Pre-Seeding Frost Workshops.
“Most proven frost mitigation tactics cannot be implemented after crops have been sown,” he said.
Mr Knell encouraged growers to remain vigilant about frost despite the State’s grain crops largely escaping frost damage in 2013.
“Every year is different and in some seasons frost induced crop losses in WA total tens of millions of dollars,” he said.
The frost workshops, initiated by GRDC Regional Cropping Solutions Networks, provided growers with management strategies, an update on the latest frost research and a review of previous research.
As well as Mr Knell, expert speakers included Ben Biddulph and Ian Foster (Department of Agriculture and Food WA), Steven Crimp (CSIRO), Rebecca Jenkinson (Living Farm) and Steve Curtin (ConsultAg).
Mr Knell outlined 10 frost management strategies and said growers should start by identifying and mapping their high frost risk paddocks, based on previous experience, landscape position and soil type.
“These paddocks should be farmed differently to reduce the financial exposure and severity of financial losses in a bad frost year,” he said.
“It’s important to focus frost strategies on the highest risk areas because some frost mitigation strategies, such as delayed sowing, can result in lost yield potential in crops that do not encounter a spring frost.”
Mr Knell said frost prone paddocks with high stubble loads could be burnt to minimise potential losses, providing the added benefit of weed control.
“High stubble loads (greater than 2.5 tonnes per hectare) appear to increase frost damage by reducing the amount of heat radiated from the soil at night, leading to lower canopy temperatures and greater frost severity, duration and damage,” he said.
“Trials funded by the GRDC Regional Cropping Solutions Network (RCSN) initiative have shown that stubble removal can reduce losses from milder frosts, producing wheat yields up to 0.7t/ha higher than in areas where stubble is retained.”
Mr Knell said crop selection was another factor to consider because frost tolerance differed between crops.
“Pasture rotations are a lower risk enterprise, while oats are the most frost tolerant crop and are 4oC more tolerant than wheat,” he said.
“Barley is 2oC more tolerant than wheat at flowering, but it is not known if barley and wheat have different frost tolerance during grain fill.
“Canola is a high risk crop on frost prone paddocks due to its high input costs.”
Mr Knell said growers needed to ensure that all wheat crops in frost prone areas did not flower at the same time.
They should also delay sowing on affected areas so that crops flowered later in the season when frosts were less likely to occur.
“Trials have found that blending a short season variety with a long season variety – such as Yitpi and Mace - is another effective strategy,” he said.
Mr Knell said the online Flower Power tool could assist growers in understanding the flowering times of varieties and their local frost or heat stress risk and help them decide on a variety and the most appropriate sowing date.
The tool is available on the DAFWA website at http://grains.agric.wa.gov.au/flower-power
Mr Knell said frost prone paddocks should not receive high rates of inputs.
“High input crops on frost prone areas are frequently more severely frosted than lower input crops with a lower target yield,” he said.
“However, ensure that crops are not deficient in potassium and copper as this can make crops more susceptible to frost damage.”
Mr Knell said crop grazing was the only way to alter a crop’s flowering time after seeding and if implemented should occur at the four to five leaf stage.
“Grazing for 14 days will delay flowering by about seven days,” he said.
Mr Knell said growers could also consider longer-term measures including claying and cultivation, although cultivation was not scientifically proven to reduce frost damage and claying was expensive.
The remaining GRDC Pre-Seeding Frost Workshops will be held at Lake King and Hyden on March 25, and Narembeen and Doodlakine on March 26.
To register, contact Alison Bailey at ConsultAg on (08) 6253 2000 or ab@consultag.com.au
Frost is a major priority area for GRDC, which is more than doubling its investment into frost research, development and extension (RD&E) to $3 million per year.
Details of current frost research projects are available in the GRDC Ground Cover Frost Supplement in the March-April edition of the GRDC magazine Ground Cover and at www.grdc.com.au/GCS109
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