University of Idaho Extension barley agronomist Chris Rogers has completed the first year of research suggesting growers may be able to cut off irrigation to their malt barley crops at the soft dough stage without sacrificing yield or quality.

ABERDEEN, Idaho — University of Idaho Extension barley agronomist Chris Rogers said his research suggests many malt barley growers have an opportunity to significantly reduce their water usage without sacrificing yields or quality.

In the first year of his study, conducted at the UI’s Kimberly Research & Extension Center, Rogers cut off irrigation to malt barley in different plots at the boot stage, which occurs when the plant’s head begins swelling within the stem; at the soft dough stage, when grain becomes mealy and the seed is devoid of liquid; and at a week past soft dough. Each treatment was replicated several times for accuracy.

The experiment has also sought to determine optimal nitrogen rates for malt barley growers.

Rogers, who used the popular Miller-Coors variety Moravian 69, will plant new plots this spring and repeat the trial. If weather or other external factors skew results, Rogers said the trial, which has received assistance from Miller-Coors, could continue for a third season.

At Kimberly, which has silt-loam soil, Rogers said eliminating a single irrigation pass reduced water use by 15 to 20 percent. As for the treatments, Rogers said the boot stage proved to be far too early to cut off water, resulting in a 46 percent yield reduction, protein levels elevated above malt specifications and fewer plump kernels.

However, Rogers saw no difference in yield quality between plots that were watered up to soft dough and plots that were watered again seven days later. He made sure the root zones of his plots remained at better than 50 percent of the soil’s capacity to hold moisture, and the soil moisture was brought to field capacity prior to each irrigation cutoff.

“Cutting off irrigation at soft dough, you can have enough water to finish off your season, assuming you’re on a soil that can hold enough water,” Rogers said.

Rogers said past irrigation scheduling studies in malt barley have confirmed similar results, but he wanted to attempt the study with a modern, high-yielding variety.

Rogers also varied nitrogen levels from 1.1 to 2 pounds per bushel, finding the maximum yield was achieved at 1.2 pounds, and then yield and quality plateaued when watering was cut off at soft dough or a week past. When water was cut at the boot stage, increasing nitrogen rates hurt yield and elevated protein, Rogers said.

Randy Grant, a Hazleton, Idaho, grower, said his fields and the Kimberly research facility have similar soil, and he also plants Moravian 69. Grant, who intends to plant 1,500 acres of malt barley this spring, typically waters past the soft dough stage. This season, however, he’ll be expected to reduce his groundwater use under terms of a recent water call settlement, and he believes Rogers’ research may come in handy.

“Most of us out in the field would agree the boot is way too early to quit watering, but a lot of us have been under the assumption that we need to water past soft dough and into firmer dough,” Grant said. “This is good data.”

Idaho Falls area farm manager Rick Passey said malt barley growers in his area are “starting to cut water off earlier all the time.”