Soaring power rates across the country have led alfalfa growers to think twice before turning on their sprinklers.

Some are developing cost-effective irrigation strategies that save them up to $30/acre, says Will Cook, University of Idaho (UI) extension educator.

“These days there has to be a good reason to apply water,” says Cook, who tracked water use in relation to water needs of several alfalfa growers during a three-year study.

In 1993, Cook and Tim Stieber, a UI water quality extension agent, started monitoring water needs of 11 southwestern Idaho producers' fields. Soil moisture sensors were installed in alfalfa fields at 1", 2" and 3" depths.

Growers found that, by monitoring and fine-tuning irrigation schedules to meet plants' actual needs, they reduced irrigation costs by as much as $26/acre. Considering the rise in power rates since 1996, Cook speculates that today those savings could run well over $30/acre.

The sensors were particularly useful in late summer and early spring, he says.

“One grower found out from monitoring his fields that he could shut his irrigation pumps off in August. By that time he had the soil profile filled deep enough to get the next cutting without additional irrigation.”

By monitoring fields in spring, Cook's growers could quickly determine whether they had enough moisture to take a first cutting before irrigating. Knowing whether or not to water in spring or late summer can also save valuable growing and production time, he notes.

“When you water and there is already enough soil moisture, it just takes longer to dry out so you can get in and take the cutting,” he says. “You pay extra both ways.”

Over-irrigating, Cook adds, can actually reduce yields by encouraging root diseases that favor moist conditions. “Phytophthora root rot can damage your root system, which leads to reduced yields and stand longevity.”

Richard Tennis' irrigation strategy? He turns sprinklers off in September — soon after the last bale from his fourth cutting goes into storage.

Tennis, from eastern Washington, says the extra month of irrigation doesn't pencil out. Rather than stretching production into October and November by irrigating for a fifth cutting, he stops at four.

He figures he gets an additional year out of his stands compared to those who irrigate into fall and take a fifth cutting. Higher power, fuel and labor costs, plus costs associated with reduced stand life, show that the return doesn't justify the expenses, Tennis says.

“I'm shooting for maximum tonnage, stand longevity and less wear on my equipment.”
— Richard Tennis

“I'm shooting for maximum tonnage, longevity of my stand and less wear and tear on my equipment. Four cuttings also fit in better with the other crops I raise.”

Although he's pleased with his existing irrigation program, Tennis views it as a work in progress. He admits that, in light of recent power rate hikes, he'll look closely at the cost-effectiveness of his four-cutting strategy.

“I may have to go from two irrigations between cuttings to only one,” he says. “That would mean I would cut sooner and then add one more cutting at the end.”

W-L Alfalfa: A Dedication to Quality Since 1958

The W-L Alfalfa Variety Line-Up:

WL 232HQ

High yield potential, exceptional forage quality, and superior winterhardiness in a late maturing variety (FD = 2.2).

WL 324

A yield leader with unsurpassed performance on poorly-drained soils. Forage Superbowl winner in 2000 (FD = 3.2).

WL 325HQ

Top yielder in University trials; unbeatable digestibility produces more milk or beef and greater profitability when fed (FD = 3.5).

WL 326GZ

A dual-purpose alfalfa variety with excellent persistence under both haying and grazing. Early maturity (FD = 3.8).

WL 342 (New!)

A very high yielding, early maturity type with unsurpassed winterhardiness characteristics (FD = 4.1).

WL 414

Well-adapted to a broad range of cutting managements and soil types (FD = 6.2).

WL 442

Very high yield potential in a semidormant (FD = 7.0) type; highly resistant to all major insect and nematode pests.

WL 525HQ

Outstanding on-farm performance in a nondormant (FD = 8.2) HQ type. High yield plus high quality produces outstanding profitability.

FD = Fall Dormancy