Nitrogen Fertiliser Requirements for Milling WheatHome

Breadmaking varieties need more nitrogen than feed varieties to get to optimal yield, even before thinking about extra nitrogen to meet protein requirements.

Defra’s NVZ rules

Nmax is a legal maximum limit averaged over the area of the crop on the farm.

Nmax for winter wheat is 220 kg/ha of nitrogen, subject to the following adjustments:

+ 40 kg/ha for milling wheat varieties

+ 20 kg/ha for each t/ha over the standard yield (8 t/ha)

+ 20 kg/ha for shallow soils, excluding shallow soils over sandstone

Growers adjusting Nmax based on yield potential must have data from at least two years to prove realistic.

“With higher yielding breadmaking varieties, it’s inevitable that more nitrogen must be available to the crop if protein levels are to be maintained. We are working with breeders to test this,” he adds.

Constraints in the form of nitrate vulnerable zones (NVZs) needn’t be an issue if you take into account all factors and keep good farm records.

If you use higher than average nitrogen fertiliser rates, you must produce a paper trail to justify your actions, says Dr Kindred.

“You must have achieved and recorded the improved yields for two years, and have an area of crop that receives less nitrogen so that Nmax limits for the crop are not exceeded,” he warns.

To estimate soil nitrogen supply, Dr Kindred recommends testing soils and using that alongside overwinter rainfall records to predict the amount. “Defra’s February-issued spring N advice states that forward crops may have captured more soil N this year. There’s probably no need to adjust rates to cover losses through the profile, since it wasn’t a particularly wet winter,” he says.

As to what type of nitrogen fertiliser to use in bread making wheat, previous research points towards extra nitrogen being most effective in the form of foliar urea applied at milky ripe (GS75), following the main dose of ammonium nitrate at flag leaf emergence (GS39).

A rate of 40kg/ha of foliar urea should improve protein levels by 0.75-1%, says Dr Kindred, with the caveat that it can be expensive and only worthwhile if the crop is borderline milling quality.

Source: http://www.fwi.co.uk/