Post-emergence application of N fertilizer to improve grain yield and quality of irrigated durum and bread wheat

Field studies were conducted for 3 yr (2001 to 2003) at two irrigated sites in southern Alberta to determine if post-emergence N application (38 kg N ha -1 ) was warranted for durum (Triticum turgidum L.) and bread wheat (T. aestivum) in soils with relatively high N. Greater efficacy occurred with in-crop surface-applied granular ammonium nitrate (AN) compared with foliar-applied urea-ammonium-nitrate (UAN) solution. Early AN application usually improved grain yield compared with the fertilized control (38 k g N ha -1 applied at seeding), while late application reduced grain yield, but increased grain protein concentration and end-use quality. Key words: Triticum turgidum, Triticum aestivum, nitrogen fertilizer, foliar, timing, split N, grain protein concentration