Brian Beres1, Byron Irvine2, John O'Donovan3, Kenneth Harker3, Eric N. Johnson4, Stu Brandt5, Cindy Grant2, Henry Janzen1, Thomas Turkington3 and Craig Stevenson6, (1)Sustainable Production Systems, Agriculture and Agri-Food Canada, Lethbridge, AB, Canada (2)Sustainable Production Systems, Agriculture and Agri-Food Canada, Brandon, MB, Canada (3)Sustainable Production Systems, Agriculture and Agri-Food Canada, Lacombe, AB, Canada (4)Scott Research Farm, Agriculture and Agri-Food Canada, Scott, SK, Canada (5)Sustainable Production Systems, Agriculture and Agri-Food Canada, Scott, SK, Canada (6)Consultant, Saskatoon, SK, Canada
This project was designed to provide information about the efficiency of nitrogen (N) management practices for western Canadian winter wheat producers. Three factors were included in Experiment 1: 1) urea type (urea, urea+urease inhibitor -‘Agrotain’; urea+urease and denitrification inhibitor – ‘SuperU’, polymer-coated urea – ‘ESN’, and urea ammonium nitrate - UAN), 2) application method (fall side-band vs. spring broadcast vs. 50% side-band: 50% spring broadcast), and 3) Cultivar ('AC Radiant' hard red winter wheat vs. 'CDC Ptarmigan' soft white winter wheat). The ‘Agrotain’ and 'CDC Ptarmigan' treatments were removed in Experiment 2 to allow for additional application methods: 1) fall side-band, 2) 50% side-band:50% late fall broadcast, 3) 50% side-band:50% early-spring broadcast, 4) 50% side-band:50% mid-spring broadcast, 5) 50% side-band:50% late-spring broadcast. 'CDC Ptarmigan' produced more grain but lower protein content than 'AC Radiant' and was superior for nitrogen utilization. Grain yield and protein content were influenced by N form and application method. Split applications of N almost always provided maximum yield and protein, particularly with ‘Agrotain’ or ‘SuperU’. In terms of yield, the UAN form, the 'ESN' form when all broadcast in spring or all side-banded in fall, and the fall-broadcasting method were inferior. An exception to the poor fall-application results was observed in the 'SuperU' treatments, which produced similar yield to the highest-yielding treatments. The results suggest split applications of N may be most efficient for yield and protein optimization when combined with a controlled release urea product, particularly with urease or urease+denitrification inhibitors, and if the majority of N is applied in spring. The overall poor performance of UAN in this study warrants consideration of an N stabilizer to mitigate the apparent losses that caused low protein and yield.