Late season nitrogen could help avoid protein dilution and make full use of milling premiums

Late season foliar nitrogen applications could still produce a return on investment of around 2:1 for milling wheat growers this year, despite rising nitrogen prices, according to Agrii.

Applications made to help maintain milling wheat yields and meet protein specifications may be particularly important where growers are targeting the current £20/t premiums on offer for the best Group 1 milling wheats.

Agrii National Fertiliser Manager, Tom Land, says missing those premiums could cost growers dearly if concerns over fertiliser prices lead them to avoid late nitrogen top-ups.

“Wheat will always prioritise growth over grain quality. So, if crops do not have sufficient nitrogen available to maintain both yield and protein as the season progresses, protein levels can fall rapidly.

“It is important, therefore, to plan ahead and understand what residual soil nitrogen is available, how much has been applied, and make sure there is sufficient available to support both yield and grain quality.”

Testing to guide late nitrogen decisions

Where there is any doubt, Tom suggests carrying out a root protein prediction test to give the most accurate guide of likely grain protein levels.

“A late season tissue test is also an option, but the root protein prediction test has proved to be the most accurate. This can be taken in late May or early June around growth stage 73, but it is important that no recent nitrogen applications have taken place.

“You can then weigh up the economics of a late foliar spray in mid-June. If you are growing a Group 2 variety without a contract, then it is probably not worth the investment.

“But if you have a good Group 1 on a solid contract with top premiums on offer, then it almost certainly will be. However, you will need to check the detail carefully.”

Calculating the potential return

The combined cost of the root prediction test and fertiliser top-up could be in the region of £85/ha, Tom says.

“If that means you get an 8.0t/ha crop that hits the protein specification of your contract, that could result in a £160/ha gain, and more if you manage to get a higher yield.

“So that is approaching a return of £2 back for every £1 spent.

“You could further boost this by using a liquid carbon source to reduce stress in the crop and make sure every kg of nitrogen is used as effectively as possible.”

Foliar urea and late nitrogen timing

Latest AHDB recommendations suggest achieving 13% protein often requires nitrogen rates to exceed 280kg/ha, with foliar urea after anthesis acting as an effective way to help achieve this, Tom points out.

“It is worth checking with your buyer, however, as some millers still have restrictions on how late nitrogen can be applied.

“If this is an issue, solid ammonium nitrate can be applied around growth stage 37 up until late May to achieve a similar effect.

“Either way, if you get your calculations correct, a late season top-up of nitrogen can be a highly cost-effective way of ensuring you achieve optimum yields of grain at the highest quality specification.”