Mint grower’s drip-irrigation success at six years

Grower Bob McKellip finds peppermint plants and roots, and a strip of drip tape five to six inches underneath, in excellent condition on his Nampa, Idaho, farm.

Six years’ worth of higher yields and lower water usage make Nampa, Idaho, peppermint grower Robert McKellip a big believer in drip irrigation.

“Drip irrigation really has its merits, and I would like to put more and more peppermint in drip because I see a big benefit,” he said.

Water savings of 40 to 50 percent, higher yields, lower fertilizer usage and much-reduced runoff are among results McKellip sees compared to the peppermint he waters via furrow and some sprinkler irrigation. Drip-irrigated roots grow down into water, which is applied precisely via a pump-and-filter station and subsurface tubing with emitters placed at intervals.

“Farmers and ranchers are currently using agricultural practices to do ‘more with less’ more than ever before in the history of agricultural production,” said Roger Batt, executive director of the Treasure Valley Water Users Association. “Some farmers have switched from furrow or sprinkler irrigation to drip irrigation on certain crops – mostly because this irrigation practice yields a better crop, but it also reduces the use of irrigation water on these crops.” Weed reduction is another potential benefit.

Drip is not economically feasible for all crops, which is good in a way, Batt said. “Our valley also benefits from recharge to our aquifer due to the 1,500 miles of canals and laterals and thousands of acres of irrigated crops using furrow irrigation,” he said.

“As time moves forward and water becomes more and more of an issue, you will see almost all high-value crops converting to drip irrigation,” said McKellip, who serves on the Canyon Soil Conservation District board. Increasing concerns about runoff also could encourage more farmers to consider it.

Drip is popular for hops and various fruits. McKellip said more growers of onions – like perennial peppermint, a high-value, high-water-use crop – now use it.

Jim Klauzer, agronomist with Clearwater Supply in Ontario, Ore., said more than 75 percent of the Treasure Valley onion crop used drip irrigation in 2017 compared to less than 3 percent in 2000. Drip-irrigated onions often are bigger, higher in quality and disease resistance, and store better, he said.

The vast majority of these onions are watered with “annual drip” systems requiring thin, tape-like tubing to be replaced and recycled after harvest, he said. But “permanent drip” systems, with more deeply set lines designed to last five to 15 years, are increasingly viable and have been used in some regions for years, he said. A recent onion-related advancement is flow-control tape suited to rolling terrain.

“We have gained confidence in a wide variety of crops, so we are promoting it for wider number of growers,” Klauzer said. Beets are viable for drip, though alfalfa hasn’t worked well because of rodent damage, he said.

McKellip installed his first drip system in 2012 with help from a Clean Water Act Section 319 grant and later expanded, shortening the original three- to four-year payoff cycle as he and the local irrigation industry gained more experience. He plans to plant some peppermint, with drip tape underneath, this year. Drip-irrigated peppermint will stay at around a quarter to a third of the total crop because he also removed some.

Challenges to investing in drip irrigation include crop prices — peppermint has been down recently — and real estate development that can reduce a farm’s future viability, he said.

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