Stubble increases frost severity
Results of large-scale field research in the Wheatbelt to quantify the impact of stubble on frost severity will be delivered this month at several Regional Crop Updates locations.
The Department of Agriculture and Food provided assistance with the trial design, management and interpretation, and Grains Research and Development Corporation funded the research through the Kwinana and Albany Regional Cropping Solutions Networks, conducted by Living Farm.
Living Farm project co-ordinator Rebecca Jenkinson said the trials were conducted in Nyabing, Wickepin and York on wheat paddocks with a history of frost events over the past 10 years.
"In addition to measuring the impact of stubble on the extent, severity and duration of frost, the research also aimed to determine the impact of stubble on canopy temperature and grain yield," she said. "The outcomes of the research will help inform growers of management options of frost-prone landscapes to help limit the economic impacts.
"The trials revealed that increased standing stubble biomass can increase the severity and duration of frost events, resulting in decreased yield at positions lower in the landscape."
Ms Jenkinson said it was unclear whether increasing stubble loads increased the severity and duration of frost higher in the landscape.
"Removing stubble (to less than 0.5t/ha) decreased frost damage and gave a yield advantage of 0.6t/ha to 0.8t/ha with a greater response in the more frost prone, lower parts of the landscape," she said.
"Strategically decreasing stubble loads in the more frost-prone parts of the landscape may therefore reduce economic losses due to frost."
The trials were sown using farmers' broadacre seeding equipment and standard cultivar, rotation and agronomic management.
DAFWA research officer Ben Biddulph said stubble treatments were replicated three times on plots 200m in length and three header widths down the natural slope of the paddocks.
The Nyabing experiment was sown with Yitpi wheat at 70kg/ha into stubble residue from a 0.8t/ha canola crop.
The Wickepin site was sown with Mace wheat at 65kg/ha into paddocks with standing (three replicates) and removed stubble (two replicates) residue treatments remaining following a 1.0t/ha to 1.5t/ha wheat crop.
Mace wheat was also sown at 75kg/ha into stubble (three replicates) and removed residue treatments on the York site.
"All sites were soil-sampled for nutrition prior to sowing to a depth of 10cm and data loggers installed in each plot measured canopy temperature at a height of 600mm every three minutes from July until harvest," Dr Biddulph said.
"Across the three sites, there was no visible effect of stubble treatment on crop emergence or plant biomass measured at maturity, and standing stubble treatments generally flowered one-to-two days later than removed stubble treatments due to lower canopy temperatures.
"Yield estimates at Nyabing based on the number of tillers and head numbers per metre squared in October indicated 4t/ha and were amended to 3.24t/ha based on limited rainfall, with lower actual yields of 2.5t/ha attributed to frost damage resulting from six frost events.
"The yield potential at Wickepin (4t/ha) and York (5t/ha), was achieved, reflecting the low levels of frost at those sites."
This work on benefits of crop management to alleviate frost is being complemented by additional work in WA to look at genetic diversity for tolerance of cereals to frost.
The research will be presented at the following Regional Crop Update locations - Katanning on March 13, hosted by Southern DiRT, and Dowerin on March 18, hosted by WANTFA.
GRDC pre-seeding frost workshops are scheduled for Brookton on March 14, Lake Grace and Nyabing on March 19, Yealering on March 20, Lake King and Hyden on March 25, and Narembeen and Doodlakine on March 26.
To register, call Alison at ConsultAg on 6253 2000 or email firstname.lastname@example.org .
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