Response of two-row malting spring barley to water cutoff under sprinkler irrigation

Agricultural production in irrigated areas is becoming more water-constrained. Scheduling the timing of the last irrigation on cereals is one effective method of reducing seasonal water use while maintaining crop yield and quality. The last irrigation application time and its impact on two-row malting barley (Hordeum distichum cv. Moravian 37) yield, quality, and economic benefits were studied in the 2000, 2001, and 2002 cropping seasons. Irrigation was stopped for the season at Milk, pre-Soft Dough, Soft Dough, and post-Soft Dough grain formation stages. The Soft Dough water cutoff treatment produced the highest grain yield of two-row spring malting barley. Water cutoff before or after Soft Dough stage reduced the grain yield significantly at P < 0.05, but the quality of grain for malt production was not significantly different when water was cut off at pre-Soft Dough or post-Soft Dough stages. Irrigation cutoff at Milk stage produced the lowest grain yield with the lowest quality. Decreases in grain yield and quality with the last irrigation at post-Soft Dough reduced grain value by $174 ha⁻¹ relative to Soft Dough, while irrigation costs were higher (Fig. 6). The economic benefit due to labor and power cost reduction from earlier irrigation cutoff does not offset the resulting loss of grain value/ha for any treatment except post-SD under current southern Idaho energy and labor cost conditions.