As featured in Arable Farming Magazine
Optimising nutrition for milling wheat
by Arable Farming Magazine September 2022 issue
Four years of field trials in an AHDB-backed research project* to help growers better meet UK millers’ needs have just been completed.
When it comes to wheat baking quality, it matters not whether the nitrogen applied to the crop is urea or ammonium nitrate.
That is one of several key points arising from research led by Dr Nathan Morris, NIAB senior specialist – farming systems and soils.
“There has been a perception in the industry that foliar urea is not considered suitable for baking quality wheats.
Yet this isn’t the case given the results from this project,” says Dr Morris.
The work aimed to update guidance on using nitrogen and sulphur fertiliser on winter milling wheat to get optimum grain quality and milling specifications for leading breadmaking varieties grown under a range of soil types and environments.
The research was originally sought by nabim, now known as UK Flour Millers.
It evaluated the impact of N and S rates and timings on dough rheology and baking performance, including (for S) the production of asparagine.
The first stage was consulting widely to home in on exactly where the knowledge gaps were regarding winter milling wheat management, he says.
“This ultimately formed the basis of field trials.
”These were conducted across six sites from southern and eastern England to Scotland.
There were two trial series, the first looking at nitrogen application rates and timings, the second examining sulphur responses.
Both investigated the impact of fertiliser on grain yield, with post-harvest grain analysis recording properties including protein, specific weight and Hagberg falling number to identify treatments that met milling specification.
Samples meeting those specifications were also sent to the Allied Technical Centre to conduct pilot milling and test baking work.
Dr Morris says the project’s main messages are: Site and season have the greatest impact on grain quality, low spring rainfall having a substantial effect on nitrogen uptake and efficiency.
August rainfall resulted in low Hagberg Falling Numbers or specific weights at some sites that would result in poor rheology and baking performance.
Grain protein increases where nitrogen (as ammonium nitrate or urea) is applied aftergrowth stage 32-35.
An extra 40kg N/ha is enough to raise grain protein for the desired specification for rheology and baking.
There was no detrimental impact on baking quality when foliar urea was applied instead of ammonium nitrate.
Where foliar urea was applied at GS73 there was a trend for the gluten to be stronger than where only ammonium nitrate was applied.
There was little consistent evidence that sulphur doses above the currently recommended 50kg SO3/ha reduce grain asparagine levels.
The research threw up few surprises, admits Dr Morris.
“Extreme weather can have a big effect on crop establishment and the crop’s ability to take up and use nitrogen.
“So, growers should be mindful of the weather around the time of fertiliser applications and be ready to adapt their strategies accordingly.
“Similarly, attention at harvest to prioritise quality wheat crops if the forecast predicts rain to minimise the risk of reducing Hagberg Falling Numbers.
“The impact of high nitrogen fertiliser prices will clearly be at the forefront of growers’ minds and it’s important to consider the break-even ratio to ensure there’s an economic return from applications.
“Achieving grain quality specification that meets UKFM needs will be essential to achieve premiums on crops for milling.”
Project could be a ‘game changer’
When the project began, independent adviser Alli Grundy says she was excited at the prospect of it shedding light on how milling wheat nutrition might be improved.
“The holy grail in my book is how the industry may more consistently increase the odds of achieving adequate grain protein season in and season out,” says Miss Grundy, who runs Cheshire-based Compass Agronomy.
“Overall, the project outcomes make a valuable contribution to the practical guidance on nitrogen and sulphur and it highlights the impact of management strategies on grain processing, such as dough rheology and baking performance.
“Being confident that you’ve supplied enough nitrogen to the crop to satisfy both yield and grain quality is a major step forward.
“In the climate of high input prices, the current status quo is to apply additional nitrogen because current guidance suggests you should, without having a mechanism to check if it’s necessary.
“However, a new protein prediction analysis was examined in the project and seemed to pinpoint with reasonable certainty whether crops did or didn’t need the traditional final nitrogen application.
“This could be a game changer in managing nitrogen.
Not only does it make economic sense to apply it only if needed but, from an environmental perspective, we need to avoid loading the system with nitrogen that isn’t going to be used by the plant and is therefore at risk of being lost.
“Revisiting the benefits of applying sulphur is also useful from an advisory perspective – particularly any new advice around changes to rate and timing.
“These practical outcomes are easily adopted by growers and are where potential productivity and quality gains can readily be made.”
• AHDB project 21140040 Nitrogen and sulphur fertiliser management to achieve grain protein quality targets of high-yielding winter milling wheat
• July 2018 to July 2022
• Led by NIAB and partnered by SRUC
• Total cost: £230,998 (AHDB investment £179,548)
• Collaborators (with in-kind contributions): Allied Technical Centre (£28,000); RAGT Seeds (£10,500); KWS UK (£4,200); Omex Agriculture (£3,750); Masstock Arable trading as Agrii (£3,500); AHDB (£1,500)