Farmers are experimenting with ways to more efficiently irrigate their crops as Nevada heads into what could be the fourth year of drought.
A closely watched experiment is underway in the Diamond Valley in central Nevada’s Eureka County, where alfalfa and Timothy hay is grown and all or nearly all irrigation is delivered via pumped groundwater.
The research is overseen by Jay Davison, a specialist in alternative crops and forage with University of Nevada Cooperative Extension and Dr. Howard Neibling, an extension water management engineer with the University of Idaho.
Late last summer, with the help of Davison and Neibling, two Diamond Valley farms installed LESA – low energy spray application – systems on center-pivot irrigation equipment as part of a three-year demonstration project funded by the county.
The nozzles on the LESA systems are about a foot off the ground, spraying into the plant canopy rather than above it, reducing evaporation and wind drift. At the same time, the pumped water pressure is nearly half, cutting energy consumption.
And soil moisture sensors constantly collecting data were installed to determine if the plants are getting the water they need and to let farmers adjust watering so crops are neither over or under irrigated.
Control systems that are currently in use, with higher water pressure and nozzles above the plant canopy, were installed as well to compare data.
“We dropped every 4 feet instead of 9.4 feet and are pumping at 20 pounds instead of 35,” says Jim Gallagher of the Eureka Producers Co-op, one of the farmers participating in the demonstration.
Gallagher says it cost about $6,000 per pivot to add the LESA system.
Everything is working, says Gallagher, but the experiment got a late start because of rains so the data so far is inconclusive.
Neibling says a similar demonstration in Arco, Idaho, has shown water evaporation was cut in half while watering below the canopy and less once the crop is cut and the nozzles are once again above the plant canopy, for an overall seasonal reduction in water use between 15 percent and 20 percent.
“It’s also a mountain valley with wind from a dry hill, same as Eureka,” says Neibling. “Using half the water (while there’s a canopy). That’s a really big deal.”
The Diamond Valley demonstration expects to collect usable data during the 2015 season. And the good news is that even if the drought subsides, conserving water and reducing energy use still makes sense.
“We have to become better irrigators or Diamond Valley will be no more,” says Gallagher. “We have time to improve system, but if we keep going as is we only have 20 years left here.”
It’s too early to tell if the drought will continue into 2015. About half of Nevada is currently considered in extreme drought, including western northern Nevada, which is in exceptional drought, the most severe rating, according to the U.S. Drought Monitor.
At the end of last year, snowpack in the central Sierra Nevada mountain range around Lake Tahoe was about 46 percent of average and 16 percent of April 1 average, according to the California Department of Water Resources.
“It’s so hard to project. Three or four major storms could provide snow in the mountains,” says Davison. “It’s impossible to predict.”
Even if the snowpack is sufficient, the way it melts in the spring matters, too. If it melts quickly, more water reaches the valleys; if temperatures vary and the snow melts more slowly, more water remains in the mountains, says Neibling.
“It’s one of the big unknowns water managers stress out over every year,” he says. “We can get a nice snowpack but get much less available for use, depending on the weather when it melts.”