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Research - Topdressing Nitrogen to Increase Grain Protein


Wheat grain must have a protein concentration of at least 10.5% (and preferably 12%) to be considered suitable for bread flour by most bakers.

The amount and timing of nitrogen available to the wheat plant is the most critical factor controlling grain protein. Supplying adequate nitrogen to winter wheat is particularly challenging for organic producers.

Nitrogen applied near the end of or after stem elongation has been shown to increase grain protein under conventional production, whereas nitrogen applied earlier in season tends to increase yield.


To test the effects of different top-dress nitrogen sources and times of application on winter wheat yield and grain protein to develop an effective fertility strategy for organic farmers to achieve bread baking quality.

young wheat wheat wheat

Results from a 2009 preliminary trial:

  • In a preliminary study conducted last year, N topdressed at tillering increased grain yield but had no effect on grain protein, whereas N topdressed at the boot stage increase protein concentration.
  • Chilean nitrate was twice as effective as chicken manure at increasing grain protein.

Increase in grain protein due to topdress treatment
  Application rate
 Topdress N Source  20 lbs N/acre  40 lbs N/acre
 Chilean nitrate  7%  15%
 Dehydrated chicken manure  0%  7%

Costs of topdress N sources:
 Per lb of product  Per lb of N
Chilean nitrate (16-0-0) $0.50 $3.15
Dehydrated chicken manure
- Cheep Cheep (4-3-3) $0.26 $6.69
- Nutriwave (4-1-1) $0.10 $2.50

Acknowledgement: This research is supported by the U.S. Department of Agriculture, National Institute of Food and Agriculture, Organic Research and Extension Initiative under Award No. 2009?01366, “Enhancing farmers’ capacity to produce high quality organic bread wheat.”

University of Maine; University of Vermont Extension, Cultivating Healthy Communities

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