Idaho researchers testing benefit of drip-irrigated mint

Nampa, Idaho, farmer Robert McKellip checks one of his mint fields being irrigated with a drip system in August. McKellip believes field trials at University of Idaho's Parma experiment station will ultimately prove the benefit of growing mint on a drip system.

PARMA, Idaho — Field trials meant to test the viability of growing mint on a drip irrigation system have shown some promise but researchers say the ultimate conclusion is still pending.

Mint irrigated with a drip system outperformed mint irrigated with a furrow system during the first year of the trial in 2013 but the furrow-irrigated mint returned the favor this year.

University of Idaho researchers said this year’s outcome was probably the result of using too little water. Mint grown on a drip system at UI’s Parma experiment station was given 12 inches of water this year, while the furrow-irrigated mint received 30 inches.

“Mint is a pretty thirsty plant and ... I really think we didn’t apply enough water on our drip mint this year,” said Parma superintendent Jim Barbour.

Jerry Neufeld, UI’s Canyon County Extension educator, said he wouldn’t read too much into this year’s results given the amount of water applied to the drip-irrigated mint.

“It’s too early to draw any conclusions,” he said. “I think it’s promising but we have to give it some time for us to get results.

Nampa farmer Robert McKellip became the first Idaho grower to put mint on a drip system in 2012 and a few others have followed suit.

McKellip, president of the Idaho Mint Growers Association, said he has reduced the water usage on his drip-irrigated mint by half, is using 30 to 40 percent less fertilizer and his yields have increased 10 to 20 percent, compared with his furrow-irrigated mint fields.

“Every year I put more mint acres under drip,” he said. “It’s a little expensive but I’ve had really good results.”

McKellip puts about 25 inches of water on his drip mint and 50 on his furrow mint. He believes the Parma trials will ultimately prove the value of drip-irrigated mint but it will take some time.

“There’s a lot of interest in it,” he said. “Before a new idea is going to be accepted, you have to prove it’s better than the old way of doing it.”

Caldwell farmer Tony Weitz, chairman of the Idaho Mint Commission, irrigates his onions with a drip system and he said drip-irrigated mint looks promising and is something he would consider using.

However, he’s concerned about the longevity of the drip tape because in mint fields, it’s left in the ground for several years.

“My biggest concern is how the tape will hold up after being in the ground for several years,” he said. “I think it’s a good concept (but) I’m worried about the longevity.”

That and other possible issues like gophers are concerns the Parma trials are meant to address, Neufeld said.

Gophers are a major problem in alfalfa fields and he has advised farmers not to use drip systems in alfalfa because they can cut right through the tape if their tunnels are perpendicular to it.

“I don’t think gophers will be as big of a problem in mint but we don’t know that yet,” he said.

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