Mar 18, 2011

California growers turning to center-pivot

Center-pivot irrigation could become the wave of the future in California, where farmers are looking to maximize water efficiency and minimize labor costs. About 30 growers attended a meeting recently in Five Points, Calif. – hosted by the Center for Irrigation Technology – to learn more about center-pivot irrigation.
Although Midwestern farmers have traditionally used pivot systems the most, more California farmers are starting to show interest.

“The reason why California hasn’t adopted the pivot system is because California has always had vast quantities of water, huge labor pools and an infrastructure of concrete ditches that delivered water. That system was super successful and people made a lot of money,” said Ray Batten of Valmont Irrigation, who spoke at the meeting.

All that’s changing now, because of the dwindling water supplies and smaller and more expensive labor pools. While pivot irrigation, like drip, is 90-95 percent efficient, the big advantage of pivot is that it requires much less labor than drip, Batten said. Unlike drip, center-pivot systems don’t have lines that need to be checked regularly to prevent clogging, or problems with root intrusion or rodent damage.

As an example of how much labor center pivots can save farmers, Watts Brothers Farm in Washington, which sits on 25,000 acres of sandy loam and clay soils and produces a variety of row crops, now uses a 200-pivot irrigation system, Batten said.

“They used to have 200 guys in the irrigation department. Today they have 20 people doing irrigation,” Batten said.

John Diener, who has used center pivots on about 1,300 acres of his sugar beets, alfalfa and corn over the past five years in Five Points, said he’s been able to save money with pivots. On average, Diener said he’s spent $160 an acre in his alfalfa fields to lease the center-pivot systems.

“Before that, we were spending $240 an acre in labor with our sprinkler system just to move the irrigation systems around,” Diener said. “And that was just in labor, not even counting materials.”

Drip requires less labor than sprinklers, but the labor for drip still adds up to $60 to $70 per acre, as opposed to about $10 per acre for pivot, Diener said.
The one big drawback with pivot irrigation is that the system works best with circular fields. Growers end up losing about 22 percent of their acreage when they convert their square fields to circles, said Ismael Diaz of Rain for Rent in Bakersfield, Calif.

There are options for farmers who want to try center-pivot irrigation but want to continue farming the corners of their fields. They can try swing arms that attach to the ends of the pivots and water the corners of the fields. Or, they can use drip systems in the corners.

Those alternatives get costly, though, and after the first couple of years most farmers opt to fallow the corners, said Jason Parker of Lindsay Sales & Service in Omaha, Neb.

On average, pivots deliver 1,300 gallons of water per minute and cost $50,000 to $80,000 each, Diaz said. One of the advantages of the newer high-tech pivots is the centralized technology that monitors every aspect of the system.

“The new control technologies have alarms that go off if the system shuts down, which let you know exactly which system shut down and when and where,” Parker said.

The computerized pivot irrigation system keeps precise records of how much water goes into the fields.
Another perk of the center-pivot system is that gravity pushes the water from the top down over the fields, which seems to do a better job of leaching salts out of the soil than drip, Diener said.

“With the drip system, you have downward movement with the water but you also have upward movement and side movement, and there never seems to be enough water to push all the salts down,” he said.

Overall, Diener’s had a lot of success with center-pivot irrigation. The one big problem he ran into was finding a way to keep the wheels in the pivot system from getting stuck in the tracks of the wheel wells.

“One person suggested that we put gravel in the tracks, but I said that our whole purpose was to take rocks out of the field, not to take them into the field.”
So, Diener began laying down almond chippings along the wheel wells.

“You just grind up the almond chips and haul them out to the field with a silage wagon and feed them into the furrows of the wheel wells,” he said. “The tires stand up on top of them. You don’t do this in all fields; only in fields where the wheels getting stuck is an issue.”

Diener is in the process of installing a center-pivot system in a 130-acre tomato field. Tomatoes are trickier than many other crops, because once the fruit starts “pinking,” the plants become susceptible to bacteria and fungal diseases if they get water on them.
Diener is going to use a center-pivot system that waters the plants from overhead until the fruit turns pink. After that, he’ll have the sprinkler heads removed and use pieces of hose from the overhead system that will be dragged along the ground inside the actual furrows to water the plants on either side of his 60-inch beds.

Rick Hanshew, an irrigation specialist with Agri-Valley Irrigation Inc., said there are many applications center pivots can be used for. Over the past two years, large carrot producers have been using center-pivot systems. Carrots and other vegetables grown from seed can be tricky to use with the overhead systems, since the germinating seeds are usually only one-quarter of an inch deep.

To combat that, growers can use more sprinkler drops with the pivots, which create finer sprays of water.

“With these systems, you can create your own micro climates,” Hanshew said. “People only use them in high-wind areas where the wind dries off the top crust of the soil. You have to keep the soil moist. But at the same time, you don’t want the irrigation water to push the seedlings off the seed line. With the overhead pivots, you’re able to do both things at once.”
By Lisa Lieberman