Baseline Advice: Late nitrogen
LATE SEASON advice on getting nitrogen applications right and ensuring the correct grain protein
Late Foliar Urea – Grain Protein – N Use for 2004
THERE ARE several reasons why it is getting harder to achieve desired grain proteins in high yielding wheats, says ADAS‘s Peter Dampney.
“Yields have risen every year. We have better varieties and improved fungicides, both of which have boosted output.”
However, nitrogen use has not increased correspondingly, he notes.
“It has either remained constant or declined.”
That has reduced proteins, especially in high yielders like Xi19.
Another factor is that the basis for national standard fertiliser recommendations is older, lower yielding varieties.
This is being addressed in an HGCA-funded project.
“It has been set up to see if newer varieties have different nitrogen requirements and if so, to find the best ways of applying extra nitrogen.”
For now, growers should accept that late foliar urea gives the highest grain protein lift, says Mr Dampney.
“It‘s also the cheapest way to achieve a protein boost.”
As a rule of thumb, the more nitrogen applied, the more protein rises. “But the form of nitrogen can be important.”
Applying solid N at flag leaf or flowering may affect the level. “But it won‘t be as great as with liquid urea.
“There is also a risk that if you have a dry spell, it won‘t work. Solid nitrogen needs to dissolve, move into the soil and then get taken up.
“Last year was a good example of how this approach can fail. There wasn‘t enough moisture.”
Applying late foliar urea at the early milk to milky ripe stage is the preferred method, says Mr Dampney.
“The big question is how much. There is no reliable technique for predicting grain protein at harvest.”
Another HGCA project aims to resolve that. Work at CCFRA is exploring testing milky ripe ear samples to see whether this can give a reliable idea of the end result.
“This will be extremely useful. Although it is relatively easy for growers to increase proteins at the moment, they have no idea how much N they need.
“Once this work is complete, it will be a far more precise science.”
This season Mr Dampney advises relying on experience.
“Look at how much nitrogen you used in the past and what grain protein levels you achieved.
“Many growers are coming to the conclusion that they should be putting more nitrogen on at this late stage.”
For high yielding varieties that makes sense, he agrees.
“But don‘t forget that high rates can cause crop scorch. There may be a case for splitting applications. This will be clearer when the research has been done.”
The standard 30-40kg/ha (24-32 units/acre) costs about £12/ha (£4.85/acre), he estimates.
“That may not be enough. Growers have gone up to 60kg/ha and seen a lift of 1-1.5%.”
With a 10t/ha (4t/acre) crop and premiums of £10/t, there is £100/ha (£40/acre) at stake, he points out.
“It costs less than £20/ha to apply foliar urea. So it‘s worth doing to the right crops.”
Making sure that only those that need it actually get it is trickier, he accepts.
“The other factor is likely premiums. Some years they may not be worth chasing.”
Another complication is soil N, of which there may be more this year.
“If there‘s more nitrogen in the system, proteins could be higher anyway. So much will depend on yields.”
Look in the next issue of Farmers Weekly for the latest Baseline Advice.
