Enhanced nitrogen management strategies for winter wheat production in the Canadian prairies

To address knowledge gaps around enhanced efficiency urea fertilizer efficacy for nitrogen (N) management, a study was designed to improve integrated nutrient management systems for western Canadian winter wheat producers. Three factors were included in Experiment 1: (i) urea type [urea, urea + urease inhibitor-Agrotain (R); urea + urease and nitrification inhibitor-SuperU (R), polymer-coated urea-Environmentally Smart Nitrogen (R) (ESN (R)), and urea ammonium nitrate (UAN)], (ii) application method (side-band vs. spring-broadcast vs. 50% side-band: 50% spring-broadcast), and (iii) cultivar (AC Radiant hard red winter wheat vs. CDC Ptarmigan soft white winter wheat). The Agrotain (R) and CDC Ptarmigan treatments were removed in Experiment 2 to allow for additional application methods: (i) fall side-band, (ii) 50% side-band - 50% late fall broadcast, (iii) 50% side-band-50% early spring broadcast, (iv) 50% side-band-50% mid-spring broadcast, and (v) 50% side-band-50% late spring broadcast. CDC Ptarmigan produced superior grain yield and N utilization over AC Radiant. Grain yield and protein content were influenced by N form and application method. Split applications of N usually provided the maximum yield and protein, particularly with Agrotain (R) or SuperU (R). Conversely, the UAN and ESN (R) forms, when all broadcast in spring, all side-banded in fall, or with late fall broadcasting, performed poorly. An exception to the poor fall-application results was the SuperU (R) treatments, which produced similar yield to the highest-yielding treatments. The results suggest that split applications of N might be most efficient for yield and protein optimization when combined with an enhanced efficiency urea product, particularly with urease or urease + nitrification inhibitors, and if the majority of N is applied in spring.