Methods of supplying nitrogen fertiliser to support growth and protein content of arable crops will need to change markedly as nitrogen application comes under increasing environmental scrutiny, says ProCam agronomist, Ian Jackson.

As plans are made for summer nitrogen applications to boost grain protein in milling wheat, he says this will be a key timing where alternative methods can be tried.

“There’s often a considerable gap between the amount of milling wheat grown in the UK and the amount that actually meets milling specification,” explains Mr Jackson.

“Although some of this shortfall is down to low specific weights or low Hagbergs, some of it is down to low grain protein. It is important to tackle this,” he adds.

With environmental restrictions on the total nitrogen dose that can be applied to crops over the season, and pressures to cut ammonia emissions under the government’s Clean Air Strategy, Mr Jackson says alternatives to traditional granular or urea forms of nitrogen are set to become increasingly important.

This will especially be the case later in the season as it becomes warmer and drier, in order to cut down on volatilisation of ammonia, and because granular nitrogen requires soil moisture for good plant uptake, he says.

“As an alternative to both granular fertiliser and liquid urea, which is often used as a later-season alternative to granular nitrogen, experience on farms over recent years has shown that applying modified forms of nitrogen has given good results.

“Applied as foliar sprays, these treatments contain nitrogen in a form that plants can readily utilise – it doesn’t have to be metabolised. This means it can be applied to the plant at relatively low dose rates. Also, because it is absorbed by foliage rather than roots, it is less reliant on moisture for plant uptake.”

Both of these factors make these types of treatment an environmentally efficient way of applying later-season nitrogen, believes Mr Jackson.

He says: “These treatments seem to produce a consistent effect. By applying a reliable source of nitrogen you are more likely to achieve grain protein specifications.

“Looking ahead, it makes increasing sense to begin fertiliser programmes with granular nitrogen earlier in the season, when soil moisture levels are higher, before moving to repeat low doses of modified nitrogen as the season progresses.

“For milling wheat, I would look at applying modified nitrogen fertiliser once or twice when the crop is in ear.

“Some of these modified treatments also feature formulations that give slower release of nitrogen, aimed at improving crop safety. Plants can be easily stressed during hot and dry weather. Even so, it’s still better to spray during cooler parts of the day.”