Crop grazing can reduce early sowing frost risk
Grain growers in frost prone areas should not be afraid of taking the opportunity to sow wheat early, if moisture is available, as the risk of damage to crops can be reduced using crop grazing to delay flowering.
This is the message from Steve Curtin, of agricultural consultancy ConsultAg, who last year helped coordinate crop grazing trials in Western Australia’s Great Southern region, supported by the Grains Research and Development Corporation (GRDC).
The trials were conducted by the Department of Agriculture and Food (DAFWA) and ConsultAg, and instigated by the GRDC’s Albany port zone Regional Cropping Solutions Network (RCSN) after it identified frost as a research priority for local growers.
Mr Curtin presented results from the Newdegate trial site to this year’s Agribusiness Crop Updates, supported by the GRDC and DAFWA.
He said that if growers sowed wheat early, they could predict the flowering date for the particular variety using the online diagnostic tool Flower Power, available on the DAFWA website at http://grains.agric.wa.gov.au/flower-power
“If the flowering date is predicted to fall in the main frost window, growers may then opt to graze the crop to push the flowering date backward,” Mr Curtin said.
The trial work identified a rough ‘2:1’ rule of thumb that growers could use for estimating the extent of the flowering delay caused by crop grazing.
“At the Newdegate trial site, we found that early simulated grazing of crops for 10 days delayed flowering by four days; 20 days of grazing resulted in a 10 day delay, and grazing for 30 days extended flowering by 13 days,” Mr Curtin said.
He said growers considering using crop grazing to mitigate the risk of frost damage should:
- Sow the crop early to maximise early growth;
- Use only long-season varieties;
- Graze crops early to optimise crop recovery;
- Use the ‘2:1’ rule of thumb for estimating flowering delay from grazing.
At the Newdegate trial site, established in a very frost susceptible area, whipper snippers were used to simulate grazing of the crop to a height of 3cm to 5cm.
‘Grazing’ started when the crop had reached the four-leaf stage – four weeks after sowing on May 14 – and 10, 20, 30 and 40 grazing day intervals were assessed.
The trial also investigated a later grazing start, seven weeks after sowing, with grazing for 10 and 20 day intervals.
A series of severe frosts occurred at the trial site on September 13, 23 and 28.
In non-trial areas of the same paddock, pockets of ungrazed wheat which were not frosted yielded 2.2 tonnes per hectare – showing the good potential of the crop in the trial area.
“But ungrazed wheat in the trial area was hit badly by frost, losing most of its potential and yielding only 0.2t/ha,” Mr Curtin said.
“All the frosted trial plots which were grazed produced higher yields than the ungrazed plots.
“This ranged from $46 to $92/ha in additional yield, not including the value of the grazed crop for sheep feed.
“For 20 days of ‘grazing’, the value of the grazed crop as sheep feed was an extra $70/ha if the amount of crop ‘grazed’ was valued at equivalent grain prices or $25/ha if valued at agistment rates.”
Mr Curtin said the trial results showed that using grazing to delay flowering in wheat crops could deliver yield benefits during seasons when frost occurred.
“But when there are multiple frost events, it is hard to avoid them all, even if flowering is delayed,” he said.
The GRDC RCSN initiative provides enhanced opportunities for WA growers to influence future investment decisions to ensure research outcomes that provide solutions to on-farm problems, and increase yields and farm profits.
As well as initiating smaller projects, RCSNs feed issues into the standard GRDC investment process which leads to bigger projects.
People who want to become a RCSN representative are encouraged to express their interest. More information about the RCSNs, including contact details, can be found at www.grdc.com.au/rcsn
AUDIO DOWNLOAD: Click here to download an audio grab for this release. Audio is of Steve Curtin.
PHOTO CAPTION: Steve Curtin, of ConsultAg, says grazing wheat crops in winter to delay flowering has been found to reduce grain yield losses from spring frosts in lower rainfall parts of WA’s Great Southern.
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