John T. O'Donovan1, George W. Clayton2, Cynthia Grant3, K. Neil Harker1, T. Kelly Turkington1, and Newton Lupwayi2. (1) Agriculture and Agri-Food Canada, 6000 C & E Trail, Lacombe, AB T4L 1W1, Canada, (2) Agriculture & Agri-Food Canada, 5403-1st Avenue S, Lethbridge, AB T1J 4B1, Canada, (3) Agriculture & AgriFood Canada, Box 1000A RR 3, Brandon, MB R7A 5Y3, Canada
Seed-placed nitrogen (N) in the form of urea can be a popular option for barley producers in western Canada since it allows seeding and fertilizer application to be accomplished simultaneously with minimal soil disturbance. However, seedling damage can occur from excess seed-placed urea. The objective of this study was to compare the effects of seed-placed and side-banded N applied at different rates, and to investigate if increasing the barley seeding rate would improve the ability of barley to overcome urea induced injury and compete better with wild oat (Avena fatua L). A field experiment was conducted at three locations in western Canada over three years. N was applied as urea at five rates (0, 30, 60, 90 and 120 kg per ha actual N) either directly with the seed or as a side-band, at three barley seeding rates (200, 300 and 400 seeds per square meter). When N was placed with the seed, barley plant density decreased, while time to maturity and wild oat fecundity increased with increasing N rate. Barley yield also decreased but only at the two highest N rates. Increasing the seeding rate increased barley plant density and improved competition with wild oat, but did not affect barley yield. Placing N as a side-band did not negatively impact barley density, time to maturity or yield, and resulted in lower wild oat fecundity compared to seed-placed N.