Sorghum and barley in southern Alberta: grain yield response to irrigation and fertilizer

The seasonal water requirements of irrigated grain sorghum, the interaction between water use and applied N fertilizer, and the comparative water use efficiences of sorghum and barley were determined in southern Alberta over a 3-yr period. Peak daily water use of 6 mm for sorghum was 1 mm lower than that determined previously for barley. Seasonal water use (500 mm) was 20% greater than for barley because of sorghum’s longer growing season. Under adequate irrigation, both sorghum and barley responded linearly to applied N up to 80 kg/ha, but when water was restricted, sorghum showed less response than barley. Water-use efficiency (kg of grain/m 3 of water used) decreased for both crops with increasing water availability but maximum yields were achieved under irrigation. When sorghum was favored with a long, warm growing season, it produced as much grain (6900 kg/ha) and used water as efficiently (1.25 kg/m 3 ) as did barley.