How to optimise nitrogen and protein in milling wheat

Growers seeking to achieve protein specification in milling wheat are being reminded to optimise nitrogen without overstepping or compromising economic thresholds.

Modern wheat varieties have huge yield potential – but growers must be realistic about whether these can be achieved on their own farms, say two advisers from agronomy company Hutchinsons.

A well-timed application of nitrogen after the flag leaf final-dressing will increase the amount of nitrogen available to crops during that crucial stage of protein development, says crop nutrition manager Tim Kerr.

Without a well-timed late application of nitrogen, crops may struggle to contain enough protein to satisfy yield and quality requirement. The later this dressing is applied then the more influence it will have on grain protein up to ear emergence.

Taking a Group 1 milling wheat targeting a protein threshold of HFN250, Mr Kerr and farm business consultant Leo Page
say growers should pose three pivotal questions around late season nitrogen requirements.

1. What is the likelihood of achieving milling wheat specification?

This is an important starting point and should be based on the historical success of meeting milling spec weight with a particular variety. If regularly or even occasionally achieved, then it would be sensible to follow past nitrogen fertiliser strategies.

If not, don’t apply additional nitrogen, it doesn’t make economic sense. Recommendations also shift with low spring rainfall. If the weather stays dry, later applications of foliar urea at the milky ripe stage will become more important.

Be aware that some milling contracts prohibit the use of foliar urea. Instead, consider forms of methylene urea applied with the T3 fungicide which is now a well-established practice. It is crop safe and reduces the need for extra field passes.

2. Should I then consider a late nitrogen application to push for protein?

Use the protein prediction test to decide whether a late application of nitrogen is needed. Hutchinsons have been using this test since 2019 and Andrew Pitts at Helix National farm uses it routinely for his milling wheat samples.

The test involves digging up 5-10 wheat plants from across a field and then sending off to the lab.  Samples can be taken from third week in May onwards.  The test retails at £36.50 per sample.

3. How can I calculate the effect of more nitrogen on my break-even costs while accounting for uncertainty and volatility?

Milling wheat requires about 5kgs extra N/tonne of wheat – so a 10-tonne milling crop needs circa 50 kgs extra N than the equivalent feed wheat crop.

Taking into account the reliability of achieving milling spec and the fertiliser product bought, this is an additional variable input cost of £5-6.50/tonne of wheat. This is money well spent when the crop is sold for an additional premium.