Record wheat yield raises the bar for Queensland irrigators

Grown under irrigation by the Bligh Family at Brookstead, the 8 tonnes per hectare (t/ha) crop showed that irrigated wheat crops are starting to reach their full potential in north-eastern Australia.

Allan Peake, a CSIRO agronomist who led the GRDC funded ‘Achievable Yields’ research project, said this result follows a disastrous season in 2008 which slowed widespread irrigated wheat production.

“In 2008 we experienced a grain-price spike that encouraged irrigated farmers to grow large areas of wheat under irrigation for the first time,” Mr Peake said.

“Unfortunately the crops in Queensland and Northern NSW realised yields of between 4 and 6 t/ha, when 7 to 8 t/ha had been anticipated. The yields were low because of widespread lodging (where plants fall over), which caused over $20 million in losses to the 2008 irrigated wheat crop,” he said.

The Achievable Yields project has set a new benchmark for high yielding wheat crops and created a set of management guidelines for growing wheat successfully in Queensland and Northern NSW.

“To achieve high yields like this record crop, growers need to use ‘canopy management’ techniques to avoid lodging,” Mr Peake said.

“In 2008 we experienced a grain-price spike that encouraged irrigated farmers to grow large areas of wheat under irrigation for the first time.”

Allan Peake

“When the young crop grows too well, the crop becomes very dense. This means the wheat plants compete for light and grow taller than they need to be, making their stems and root systems weaker, and more likely to fall over.”

Correct timing of Nitrogen fertiliser application is a key factor in preventing lodging. Mr Peake recommends that growers should not apply all of their Nitrogen fertiliser before the crop is sown, but instead apply it later in the growing season when the crop really needs it. Choice of variety is also critical, with growers advised to sow quick-maturing, lodging resistant varieties, rather than the longer-season varieties that growers often favour for dryland wheat production.

“Growers also need to be willing to irrigate the crop heavily later in the season,” Mr Peake said.

“High yielding wheat uses a lot of water in spring and should be irrigated frequently during the critical period between flag-leaf emergence and the middle of grain-filling. And don’t forget that controlling leaf disease is also vital insurance for a high yielding crop.”

The record high yield achieved by the Bligh family came about after brothers Hamish and Fraser attended a field day where Mr Peake was presenting on the new management guidelines.

After the Blighs saw Mr Peake’s presentation on the CSIRO management techniques, they decided to try and grow an irrigated wheat crop. They were seeking to grow a high yielding wheat as a quick cash crop to help recover from the 2011 floods which wiped out most of their summer crop. Wheat was a regular part of the Bligh’s crop rotation, however, they had previously only experienced yields of up to 6t/ha on their farm. 

Hamish Bligh said their good management advice was also blessed with good fortune.

“We followed the advice from Allan and each time we watered our crop, it was followed by a decent rain as well, which really gave us optimum conditions,” Mr Bligh said. “We won’t be doing wheat again this year, but next year we’ll try it again and follow the guidelines to see if we can achieve similar yields. This crop has really helped us to bounce back from the floods.”

Mr Peake encourages growers to use the newly developed guidelines for irrigated wheat.

“The high yields are definitely achievable for farmers throughout the northern grain belt if they apply the recommended management techniques, although the top yield will vary from year to year depending on the weather,” Mr Peake said.

“Avoiding frost at flowering is also critical, so if growers are trying a new variety, they need to get good advice on appropriate sowing dates for their district.

“Growers should test on a small scale and gain confidence with the new techniques before trying the new strategies on the whole farm. Different soils, paddock history and districts can all interact differently with new management techniques,” he said.

“And there is no silver bullet that will completely eliminate lodging risk in the most severe storms. Even in the UK, where they have bred high-yielding wheat varieties that stand just 70cm tall and use plant growth regulators to strengthen the crop, they can still experience lodging.”

The management guidelines are available in Mr Peake’s paper from the 2011 ‘Goondiwindi Update’ conference, which will soon be available on the GRDC website .