CENTRAL Queensland irrigators keen to improve irrigated wheat yields within their cotton rotation are being encouraged to trial altered agronomic strategies on small scale areas.
Queensland Primary Industries and Fisheries cotton extension officer Susan Maas who works in cooperation with the Cotton Catchment Communities CRC and the Cotton Research and Development Corporation organised a June 16 Irrigated Grains information meeting at Emerald attended by 25 growers and agronomists.
Ms Maas said there was limited research data to assist Central Highlands and Dawson-Callide regions’ 60 specialist irrigation growers to consistently produce high yielding, high quality wheat to take advantage of high value market windows.
“Crop lodging has been identified as the biggest hurdle for irrigated wheat producers wanting to maximise yields and the problem is an even bigger challenge for Central Queensland growers who are reliant on crop recommendations based on southern cropping experience,” Ms Maas said.
The Emerald meeting was addressed by Toowoomba-based CSIRO Farming Systems researcher Allan Peake, an irrigated grains production specialist who leads the Grains Research and Development Corporation-funded “Achievable Yields” project. New Zealand research agronomist Nick Poole, a research coordinator for a GRDC-funded irrigated wheat canopy management project, discussed improved timing of nitrogen and fungicide applications in high yield wheat.
Mr Peake explained to growers that lodging is caused by shading within the crop canopy which weakens the stems and reduces surface root growth.
“It is suggested that high levels of nitrogen and high plant populations are the two most common agronomic factors that cause excessive vegetative growth during tillering which increases the lodging risk through increased shading,” Mr Peake said.
“Based on southern experience, the cropping strategies to counter high soil nitrogen are to plant later in the season, select quicker maturity varieties or sow less seed.
“The key advice is not to make knee-jerk reactions – just change one thing at a time and see what happens otherwise the paddock yield might be reduced.”
Mr Peake said there was a tendency for growers to use high plant populations when growing irrigated wheat when the dryland plant densities of around 100 plants per square metre may be sufficient.
“Wheat can tiller prolifically and by allowing the crop to slowly increase stem numbers through tillering, it will improve light penetration into the crop canopy over a longer period,” he said.
Mr Peake said that decreasing soil nitrogen at sowing and applying more of the nitrogen in-crop could have a similar effect to reducing the plant population.
“A mild nitrogen stress through tillering can decrease the crop leaf area while having little impact on tiller numbers.
“Growers elsewhere in the world have been able to reduce lodging risk and improve nitrogen use efficiency by holding the nitrogen back until the start of stem elongation.”
Mr Peake issued a caution for those growers who like to enthusiastically trial new practices.
He said that because the wheat growing season was much shorter in Central Queensland, any new ideas coming out of the south should be trialled using small areas first. There was always a risk that these agronomic changes could have a greater impact than intended in a new cropping environment.
Ms Maas said the grower feedback indicated they would be prepared to trial the innovative agronomic practices on small scale areas to reduce the potential for crop lodging while striking a balance to target achievable yields.
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