Milling wheat may need late foliar N this season

High yield potential crops coupled with significant spring nitrogen losses from the wettest April on record mean late foliar nitrogen may be particularly important for many milling wheat to make the required protein specification this season.

That is the message from Agrii crop nutrition technical manager, David Langton, who says additional sulphur could also be worthwhile where higher sulphur losses through leaching have reduced efficiency of nitrogen use.

He says: “With most wheats looking set to yield particularly well this year, grain proteins are likely to be diluted to a far greater extent than last season. At the same time, more than 200mm (7.8in) of spring rain will almost certainly have led to noticeable losses of applied nitrogen in many cases. Leaching will have been the main culprit on light and shallow soils, while heavier ground that suffered water-logging could have seen N losses of up to 25 per cent through denitrification by soil bacteria.”

If sufficient extra ammonium nitrate was not applied at the flag leaf or foliar N with the T3 spray, Mr Langton advises growers to consider around 40kg N/ha as liquid urea by the end of the milky ripe stage wherever late foliar nitrogen is permitted by end-users.

Protein boost

"Our trials and others have typically shown a protein boost of 0.75-1.00 per cent from a 200 litres per hectare application of Protol liquid urea delivering 40kg N/ha,” says Mr Langton.

"A more reliable protein lift than we see with either solid AN or earlier-applied urea, this is likely to be particularly cost-effective in a season in which high protein milling wheats could well be in far shorter supply than of late.”

For the greatest effectiveness, applications need to be made when the crop is at the milky ripe stage. Early evening spraying is always preferable to minimise N losses through volatilisation in the heat of the day. And tank-mixing should be avoided to minimise scorch risk, he adds.

The extent to which late nitrogen will be valuable this season will depend on the particular protein efficiency of the varieties being grown, as much as the specific crop circumstances.

"Our milling wheat systems trials highlight major differences between modern varieties in the efficiency with which they build grain protein.

"This and the care that needs to be taken to ensure applications comply with NVZ restrictions in addition to end-user production protocols makes it vital to plan applications carefully.”