Western Australia
February 23, 2018
DPIRD research officer Shahajahan Miyan assesses the base of a wheat plant for crown rot infection at the department’s Merredin Research Facility as part of research on sustainable continuous wheat cropping.
Research in the eastern Grainbelt has opened the door to more flexible options for cropping scenarios that demand continuous wheat sequences – provided paddock constraints are managed diligently.
Continuous wheat sequences have become more prevalent, particularly in low rainfall areas, driven by seasonal conditions and short term economics that favour wheat production.
However, continuous wheat production is at increased risk of grass weeds, soil borne pathogens and plant nutrition exhaustion.
The Department of Primary Industries and Regional Development is undertaking a four year trial, supported by the Grains Research and Development Corporation (GRDC), which compared the impact of these constraints on yields across different crop sequences.
The results from the first three years of the trial at its Merredin research facility will be discussed at the 2018 GRDC Grains Research Updates in Perth next week.
The trial assessed six sequences involving combinations of wheat, canola and fallow in paddocks with high levels of ryegrass and crown rot.
The research showed that there was little variation in overall yield results between sequences, however, there were variations between the three wheat varieties used in the trial – Mace , Magenta and Emu Rock .
Department senior research officer Bob French said while the trial confirmed wheat-on-wheat paddock sequences without a yield penalty to at least four years were possible at the Merredin site, he stressed the importance of flexible crop rotations.
“Crop rotation provides a valuable tool to keep yield threats at bay and to improve soil condition through the inclusion of pasture and grain legumes,” Dr French said.
“Flexible management strategies are required in years, or in a sequence of years, to optimise yield potential where sowing crops other than wheat would not be viable or profitable.”
The Merredin trial results showed that Emu Rock experienced lower levels of crown rot infection and yields were subsequently 11 per cent higher than Mace and Magenta in 2017, averaged across the sequences.
“Given this tolerance, Emu Rock could be a more profitable option for continuous wheat sequences in paddocks with high levels of crown rot inoculum in the soil,” Dr French said.
The trial also revealed crop competition was imperative to keep rye grass levels low and boost yields.
“There was little difference in weed numbers between wheat varieties in the 2015 and 2016 trials, but in 2017 there were twice as many rye grass heads in Emu Rock as in Mace or Magenta,” Dr French said.
“We attribute this to poor crop competition, as Emu Rock established fewer plants than Mace or Magenta, possibly due to poor seed quality.”
The trial also highlighted the importance of maintaining good ground cover in fallow plots, to ensure good water storage and soil conditions, as well as a partial disease and weed break for crops the following year.
In soils prone to sealing, ground cover helps rainfall infiltrate and reduces surface evaporation, which increases fallow water storage and helps maintain good seedbed conditions in seasons with a dry start.
The trial will continue in 2018 with the addition of a new variety, Scepter, to compare variety performance, while crops will be sown on and between rows to assess crown rot mitigation.
The 2018 GRDC Grains Research Update are on Monday, 26 and Tuesday 27 February at Crown Perth. Further information is available on the Grain Industry Association of Western Australia’s website.
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