RESPONSE OF SILAGE AND GRAIN CORN TO IRRIGATION AND N FERTILIZER

Abstract

An early corn hybrid (Warwick SL209) and a medium-maturing hybrid (Idahybrid 330) recommended in southern Alberta for grain and silage, respectively, were not irrigated or were irrigated until early July, late July, or for the entire growing season. When rainfall was 126–163 mm during May to September (40–77 mm less than normal), irrigating throughout the growing season was required for maximum whole-plant yield of Idahybrid 330 and to late July or for the entire growing season for maximum yield of grain of Warwick SL209. When rainfall was 312 mm (109 mm more than normal), irrigation was required only until early July for maximum whole-plant yield and was not required for maximum yield of grain. With soil water nonlimiting and low soil test NO3-N, maximum yield of grain occurred when fertilizer N was applied at 84 kg/ha and maximum whole-plant yields tended to occur where N was applied at 252 kg/ha. Evapotranspiration (ET) peaked between 5 and 7 mm/day.