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.”