In-crop application effect of nitrogen fertilizer on grain protein concentration of spring wheat in the Canadian prairies

Abstract

Due to the price premium for high-protein wheat (Triticum aestivum L.), many producers are interested in the efficacy of in-crop application of low rates of N fertilizer for increasing grain protein concentration (GPC). We conducted field studies at 26 site-years in Alberta, Saskatchewan and Manitoba from 1998 to 2000 to determine if in-crop application (tillering, boot stage or anthesis) of N fertilizer [broadcast ammonium nitrate (AN) or foliar urea-ammonium-nitrate solution (UAN); 15 kg N ha-1] could economically increase GPC of a Canada Western Red Spring (CWRS) wheat cultivar (AC Barrie). Basal N fertilizer rates were 60 and 120 kg N ha-1. The average increase in GPC due to in-crop N application was 3 g kg-1. The increase in GPC was similar at basal N rates of 60 and 120 kg N ha-1. Broadcast AN and foliar-applied UAN were generally equally effective at increasing GPC, but were not more effective than application at the time of seeding. Late application tended to increase GPC more effectively than early application. The increase in GPC due to application of in-crop N was not economic at most sites in this study, but might be greater if applied under more N deficient conditions. Key words: Split N application, foliar, timing