R. Byron Irvine1, Guy Lafond2, William May2, and Randy Kutcher3. (1) Agriculture and Agri-Food Canada, Brandon Research Centre, P.O. Box 1000A, RR 3, 18th St and Grand Valley Rd, Brandon, MB R7A 5Y3, Canada, (2) Agriculture and Agri-Food Canada, Box 760, Indian Head, SK S0G 2K0, Canada, (3) Agriculture and Agrifood Canada, Box 1240, Melfort, SK S0E 1A0, Canada
The potential for overwinter losses of nitrogen by denitrification and leaching have led to the recommendation that nitrogen fertilization of winter wheat be done using ammonium nitrate broadcast in the spring. However, the recent loss of prilled ammonium nitrate as a fertilizer option has forced producers to consider other options. Some of these options include dribble banding of urea ammonium nitrate (UAN) in the spring or fall, application of urea or anhydrous ammonia at seeding and the use of coulter systems to place urea or UAN below the surface in the late fall or early spring. We applied target nitrogen application at 70% of optimal levels to allow differences between application strategies to be expressed. The use of a coulter by itself resulted in a 12% and 7% reduction in grain yield in the fall and spring, respectively when compared to the broadcast only application of ammonium nitrate. Damage from coulters could be minimized by operating them right angles to the direction of planting or by the use of guidance systems to operate between the rows. Urea at the time of seeding had 7% lower yields than broadcast ammonium nitrate. While spring broadcast urea had only a 5% reduction in yield relative to broadcast ammonium nitrate, urea is more subjected to losses due to volatilization than side-banded urea at planting. However, if soils are subject to high moisture levels in the spring, fall banded urea may be lost due to denitrification and leaching. In this study spring dribble banded UAN yielded 98% of spring broadcast AN. There is evidence from other studies that anhydrous ammonia or urea combined with nitrification inhibitors and coated urea reduce the risk of nitrogen loss when nitrogen is applied at planting.