See more from this Session: Organic Management Systems Community: I
Tuesday, October 18, 2011: 4:00 PM
Henry Gonzalez Convention Center, Room 207B, Concourse Level
Wheat grain must have a protein concentration of 12% or greater to be considered suitable for bread flour. The most critical factor controlling grain protein is the amount and timing of nitrogen (N) available to the wheat plant. Supplying adequate N to winter wheat can be challenging, particularly for organic producers. Nitrogen applied after stem elongation has been shown to increase grain protein under conventional production, whereas N applied earlier tends to increase yield. The objective of this trial was to test the effects of two different OMRI-approved sources of top-dress N (Chilean nitrate (CN) and dehydrated chicken manure (DCM)) at three times of application (tillering, flag leaf, and boot) on soil N availability, winter wheat N uptake, grain yield, and grain protein. Duplicate trials in Maine and Vermont were conducted in 2010 and 2011. All plots received approximately 78 kg available N ha-1 as manure before planting wheat (c.v. ‘Harvard’). Topdress treatments were applied at 22 kg available N ha-1. Results from 2010 were consistent over sites. Ideal growing conditions resulted in relatively high grain yields and low grain protein; the no-topdress control treatment yielded an average 3.8 tonnes ha-1 with a grain protein concentration of 8.1%. Topdressing N did not affect yield except for the boot-stage application of CN (22% increase). Both topdress N sources increased grain protein, but CN was more effective than DCM. Averaged over application time, grain protein was 9.3 and 8.6% for these treatments, respectively. Topdressing later in the season produced greater increases in grain protein. Averaged over topdress source, grain protein was 8.6, 8.9, and 9.4% respectively for tillering, flag leaf, and boot stage applications. Results from 2010 indicate that topdressing N can be an effective strategy for organic farmers to increase grain protein. Results from 2011 also will be presented.