Canola growers could incur yield penalties of up to 30% by windrowing earlier than the recommended levels of 50-60% seed colour change.
GOA Chief Executive, Maurie Street, says trials have found windrow timing has a greater impact on crop yield than oil percentage.
This is a key finding from research conducted by the Grains Research and Development Corporation (GRDC) sponsored Grain Orana Alliance (GOA) that originally aimed to assess windrow timing in canola and its potential influence on canola oil percentages.
But GOA chief executive officer Maurie Street said trials have actually discovered that windrow timing has a greater impact on crop yield that oil percentages.
He said it had been commonly accepted in the past that windrowing too early may reduce oil content and windrowing late may reduce yield through excessive pod shelling and shattering.
“Across the three seasons and a number of sites, early windrowing at around 5-10% colour change has consistently resulted in lower yields than later windrow timings, however, windrowing past the currently recommended 40-60% colour change sometimes showed further yield increases,” Mr Street said.
“The findings from these trials suggest that striving to meet the upper end of the current recommended windrow timings is important (40-60% colour change) and should be targeted as a minimum as significant yield penalties have been demonstrated consistently if windrowing earlier than these levels.
“However, there have been trials such as at Coonamble in 2010 and at Gilgandra in 2011 (Hertel) that have clearly demonstrated that delaying past these times have shown to further improve yields and in all of GOA’s trials they have shown trends in yields continuing to increase up to 90-plus % colour change.”
One major concern with such a practice is the risk of shattering before or during windrowing when timings are delayed. These trials have demonstrated no yield penalty from delays in windrowing except in an extreme case.
This finding could infer that the magnitude of the shattering is small and statistically insignificant against any potential yield gains over the same period.
“In deciding to delay windrowing later than 60% colour change, growers and advisors should consider that each season or indeed each paddock could be different,” he said.
“Firstly, growers and advisors should consider the crop’s current growing conditions such as terminal moisture stress beyond 60%, in which case it may not be warranted.
“But if moisture is still available, even if limited, consider that this work has shown windrowing later won’t always increase yields, but sometimes it does and windrowing up to 90% colour change has not demonstrated any significant yield decline- why not?”
Mr Street said selection of varieties with greater shattering tolerance through breeding programs, changes in plant populations and farming systems as well as better machinery may mean that pod shatter is now less significant than when the original recommendations of timings were founded.
“Direct heading has also shown to be a suitable management option for canola, demonstrating that it often matches the performance in terms of yield of a well-timed windrowing; but not compared to ill-timed windrowing,” Mr Street said.
“What these trials do aim to demonstrate is the potential economic benefit gained by getting it right. The availability of windrowers at the correct time or the other advantages offered through windrowing should be considered.”
For more information on direct heading, download the GRDC’s recently published Direct Heading Fact Sheet,which you can follow via this link.
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