Response of irrigated soft white spring wheat to seeding date, seeding rate and fertilization

Irrigated production of soft white spring wheat (Triticum aestivum L. Em Thell.) (SWSW) for pastry flour or ethanol production is feasible if the high yield potential of recently released cultivars can be realized. Field studies were conducted at three locations over a 3-yr period to determine the response of irrigated SWSW to seeding date, seeding rate and fertilization (N, P and K) in southern Alberta. The highest yield was obtained for the first seeding date (Apr. 20 to 24). Seeding 2 wk later reduced average grain yield by 3%, while seeding 4 wk later reduced average grain yield by 15%. The optimum seeding rate was 200 to 240 viable seeds m(-2) (84 to 101 kg ha(-1)). Maximum yields were achieved when total available N (fertilizer + residual soil NO3-N+ mineralized N) was greater than 26 kg N Mg-1 of potential yield. Mineralized N ranged from 45 to 183 kg N ha(-1) (mean 125 kg N ha(-1)). Grain protein concentration did not exceed the maximum allowed for protein premiums (99 g kg(-1)) when total available N was less than 27 kg N Mg-1 of potential yield. The optimum P fertilizer rate was approximately 13 kg P ha(-1) unless extractable soil P was very high. No response to K fertilizer was observed. Maximum grain yields of 7.3 to 10.6 Mg ha(-1) were achieved by seeding early with a minimum of 200 viable seeds m(-2) and application of sufficient N and P fertilizer.