In‐Season Nitrogen Effects on Organic Hard Red Winter Wheat Yield and Quality. (1st July 2013)

• Record Type: Journal Article
• Authors: Mallory, Ellen B.; Darby, Heather
• Is Part Of: Agronomy Journal. Volume 105:Number 4(2013)
• Page Start: 1167
• Page End: 1175
• Publication Date: 2013-07-01
• Subjects: Agronomy -- Periodicals; 630
• DOI: 10.2134/agronj2012.0447
• Languages: English
• ISSNs: 0002-1962

Abstract

Abstract : Ensuring adequate available N for grain protein development is a primary challenge for organic production of winter bread wheat ( Triticum aestivum L.). Topdressing organic wheat in‐season may improve grain yield and quality. The objective of this study was to determine if supplemental N topdressing at key wheat developmental stages would improve organic hard red winter wheat yield and protein concentrations. Field experiments were conducted over 4 site‐years from 2009 to 2011 in Maine and Vermont, using the variety Harvard. Treatments were a factorial arrangement of two organic‐approved N sources (Chilean nitrate, CN, and dehydrated poultry litter, DPL) and three times of application (tillering, flag leaf, and boot stages). Plant N uptake, grain yield, and grain protein concentration were determined. Plant‐accumulated N was always higher in the CN treatments than in the DPL and manure‐only treatments. The CN topdress treatments yielded on average 11% more than the manure‐only treatment and 6% more than DPL treatments. Topdressing increased grain protein concentration in all cases, although none of the treatments reached the 120 g kg –1 milling standard, due in part to variety Harvard being a low‐protein, high‐yielding variety. Chilean nitrate was more effective at increasing grain protein levels than DPL, and for both N sources, later applications were more effective than earlier ones. Topdressing could be a cost‐effective strategy to boost grain protein levels for organic winter wheat production, but further work is needed to evaluate topdressing with higher protein varieties and identify additional rapidly‐available and economical organic approved N sources.