Low energy spray demonstrations planned in Washington, Oregon
PULLMAN, Wash. — Washington State University and Bonneville Power Administration are planning demonstration projects in the Columbia Basin of Washington and Oregon to spread awareness about an irrigation innovation that’s gaining popularity in Idaho.
Growers throughout Eastern Idaho have rapidly converted pivots to Low Energy Spray Application, compelled by a recent water call settlement mandating groundwater irrigation reductions averaging 12 percent per year.
LESA uses low pressure and long hoses that spray below the crop canopy, reducing water loss to evaporation and drift. T adapters are installed throughout most of the pivot, dropping hoses on either side, spaced 5 feet apart for even distribution so close to the ground.
Bonneville Power mechanical engineer Dick Stroh said his company offers a program through its member cooperatives sharing 25 to 30 percent of LESA conversion costs. LESA packages range from $10,000 to $12,000, installed.
“In some ways, (LESA adoption) has been faster in Idaho than what we had expected, and that’s been driven primarily by the groundwater settlement with the surface water users on the Snake River Plain Aquifer,” Stroh said. “This is a way to achieve that reduction without really sacrificing much of anything.”
Stroh said LESA growers have cut water use by at least 10 to 15 percent. LESA power savings has been up to 30 percent for surface users, and ranges for groundwater users depending on their well depth.
At 10 demonstration sites within its Washington and Oregon service area, Bonneville Power will bear the cost of converting a single pivot span to LESA, allowing growers to compare irrigation efficiency with conventional spans in the same fields, using soil-moisture monitors. Grower field days will be hosted at the sites to share results with neighboring farmers. WSU Extension irrigation specialist Troy Peters, who oversaw a couple of LESA demonstrations in his area last season, has found interested participants in Oregon for the planned project but is still seeking Washington growers.
“This method will get more water per gallon into the ground,” said Peters, who helped develop LESA for the Northwest. “In some cases, (growers) would get behind with their water, and this will allow them to catch up, where before their systems didn’t have enough capacity.”
Peters also hopes to test reversing nozzle plates to spray up and out of the canopy as a means of chemigating with LESA. Peters noted LESA may not work in every situation — including soils where runoff occurs under conventional pivots and fields with variable topography — but he’d like to evaluate it in as many crops and conditions as possible.
“It’s not applicable in every situation, but I think a lot of people who aren’t doing it should be,” Peters said.
George Darrington, conservation program manager with the Bonneville Power member Raft River Rural Electric Cooperative, knows of a customer who installed two LESA systems as a means of coping with failing pivot pumps, given that LESA requires little pressure anyway.
Stroh advises growers to operate LESA systems with no more than 6 pounds per square inch of pressure to avoid erosion. Stroh also noted many growers have opted to reduce operational hours of pivots rather than cutting back on water volumes to achieve LESA savings, which could also pose erosion challenges.