Research prompts nitrogen rethink for barley
GroundCover™ Issue: 133 March - April 2018 | Author: Jo Fulwood
Research is challenging the traditional thinking that applying most of your nitrogen up-front will increase barley yields
New research is finding that delaying nitrogen application until stem elongation can improve protein levels, with no ill-effects on yield.
WA Department of Primary Industries and Regional Development senior research officer Blakely Paynter says these findings, from five years of GRDC-supported trials, go against traditional thinking that higher yields are gained by applying the majority of nitrogen up-front at seeding time.
“Previously, growers may have believed that applying all or most nitrogen up-front will promote tillering, which then equates to increased yield,” he says. “But our research illustrated that this was not necessarily the case and we can have a bigger impact on protein levels if a careful and sustained application of nitrogen occurs.”
Managing nitrogen on a barley crop, in response to seasonal vagaries, is more critical than in wheat, given that excess nitrogen can cause lodging and high screenings in barley.
“As opposed to higher-protein Australian Hard wheat, where there is a financial upside, too much nitrogen on barley can reduce grain size and increase screenings, often downgrading the grain to feed.”
The research considered a range of different variables in regard to increasing protein in barley, such as timing of nitrogen application, varietal response to nitrogen and nitrogen rates.
The series was syndicated across 23 sites in WA between 2012 and 2016.
“In many grain businesses, we are now seeing rotations without a legume, with canola as the break crop, and so therefore the only way you can increase protein in cereals is to apply fertiliser, and this is a significant cost burden,” he says.
“It is important that your nitrogen strategy be planned and carefully managed to ensure maximum return on your fertiliser investment,” he says.
Mr Paynter says there are critical times during the season for nitrogen application – at seeding time, at three to four weeks (first spray pass), at eight to 10 weeks (stem elongation) and a late-season application, often combined with a radish or fungicide spray.
“Our research has shown that applying at least two-thirds of your recommended nitrogen at stem elongation results in increased grain protein of up to 0.5 per cent (depending on rate) with no yield penalty,” he says.
The results have demonstrated that nitrogen applied at seeding and mid-tillering does not achieve the same protein results as the same nitrogen rate applied at stem elongation, often resulting in the barley not meeting the minimum protein target for receival as malt barley.
Mr Paynter says the research also illustrated that different varieties gave similar reactions to a delayed nitrogen program.
“While some varieties did start from a lower protein base, their reactions to the applied nitrogen were all very similar,” he says.
In WA, two soft seasonal finishes on barley crops have seen plump grain, low screenings and lower-than-expected protein levels.
“When a grain kernel forms, the protein goes in first, followed by the carbohydrates, meaning the bigger the grain ends up being, the more diluted the protein is,” he says. “This could be part of the reason we saw lower protein in many crops in the past few years in Western Australia.”
He says growers are considering planting newer varieties, such as Spartacus CL, but some are concerned that it may be a low-protein variety.
“Spartacus CL is a back-cross of the La Trobe–Hindmarsh family, and La Trobe is well known for being very yield-responsive to nitrogen, which often results in it achieving a lower protein level,” he says.
“While Spartacus CL has only been involved in our trials for the past two years, early indications are that it does not have the same high-yield, low-protein response as La Trobe, but we will be testing this further throughout the 2018 season.
“Through this research we are hoping to start the conversation about modifying your nitrogen application strategy so you can better manage the season and achieve more profitable outcomes from the investment you make in your fertiliser.”
He says further work on nitrogen rates will occur in coming years to give growers greater confidence in staggering their application program.
“In 2018 we will be focusing on the period between stem elongation and flag leaf emergence to see if we can increase the
protein boost observed to date without affecting yield or damaging the plumpness of the grain,” he says.
GRDC Research Code DAW00224
08 9690 2115
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