Influence of rate and timing of nitrogen fertilization on yield and quality of hard red winter wheat in Ontario

Several previous studies have reported that grain yield of cereal crops was greater from multiple than from single nitrogen (N) applications. The purpose of the study was to determine the influence of the time and rate of N application on the yield and quality of hard red winter wheat grown in Ontario. One experiment was conducted in each of 2 yr using a factorial arrangement of treatments. Factors were rate of N application (40, 80, 120, 160, 200 or 240 kg N ha−1), and timing of N application (100/0/0, 75/25/0, 50/50/0 or 25/50/25 percent of the N applied at Zadok’s growth stages 22/32/45). Early N application reduced grain yield in a year of below-average precipitation, increased grain yield in a year of average precipitation, and increased straw yield in both years. Late N application increased grain crude protein concentration and harvest index in both years. Given the lack of a consistent yield increase and the added cost of application, it is unlikely that multiple N applications will be economical for hard red winter wheat production in Ontario.Key words: Triticum aestivum, intensive cereal management, yield components, wheat