February 2012
Precision Irrigation

Irrigation technology has come a long way in the past decade, and equipment designers and manufacturers aren’t done yet. Growers can expect to see continued advances, even to center pivot systems that already have the ability to achieve 80 to 85 percent water application efficiency when properly maintained.

What kind of improvements can growers expect to see in the next few years? Look for a focus on power conservation, application uniformity, automation and precision agriculture, experts say.

Precision ag
About 15 years ago, there was a push in Idaho to install global positioning systems on center pivots, said Brice Beck, a partner and general manager at Butte Irrigation in Paul, Idaho.

Unfortunately, the sprinkler valves and communication software didn’t work as well as many had expected.
The effort fizzled.

The technology has improved dramatically since then, and some manufacturers are again working on GPS packages for center pivot systems, Beck said.

With GPS-equipped pivots, growers can precisely apply water and/or chemicals to a field, automatically adjusting selected sprinklers based on terrain, soil type or other factors.

For instance, a grower who’s chemigating a field with an open lateral running through it could set his pivot to automatically shut the sprinklers off just before reaching the lateral and then back on after the pivot was safely on the other side.

Likewise, a grower could make sure that rock piles in his field were not irrigated, thereby conserving water.
Lindsay Corp. is working on a precision ag pivot package that’s expected to be released sometime during the first half of the year, Beck said. Valmont also is developing a GPS pivot package.

While costs for such advanced systems have come down significantly in recent years, they’re still pricey.

The average cost for a complete GPS package could reach $25,000 to $30,000 by the time valves are installed on every sprinkler and all the electronics, including the GPS controller and radio receivers, are put into place.

GPS-equipped pivots come with a higher price tag and more headaches than standard systems, but they may be worth it under certain circumstances, Beck acknowledged.
Growers should weigh the costs and benefits before taking the plunge.

“I think we may install one in the next few years, but before there are a dozen of these systems in our area it could be five to 10 years,” he said.

Lower power consumption
As energy costs continue to climb, there will be an increased need for irrigators to reduce their power consumption, said Howard Neibling, a University of Idaho Extension water management engineer.

The most obvious way to accomplish that is to reduce system pressure.

When center pivots were first introduced they sported top-mounted impact sprinklers and probably produced 60 to 70 pounds of pressure per square inch at the pivot point, Neibling said.

“Now, it’s not unusual to see a system on fairly flat ground that’s maybe 35 psi at the pivot point,” he said.
New drop nozzles, pressure regulators and other devices made by companies such as Nelson and Senninger have helped to significantly reduce overall power consumption while improving uniformity.

“They are continually coming up with new devices that do a better job of applying the water at lower pressure,” Neibling said. “I think that will continue to happen. Competition will drive improvements.”

The quest for uniformity
Major spud buyers and consumers are demanding a more uniform product all the time, Neibling said.

But producing a nice uniform potato crop can be a challenge because spuds are a particularly water-sensitive crop. Too much variation in the amount of water applied to the field can easily produce areas of poor quality.

The move in recent years to variable frequency drives has helped improve pump efficiency and crop watering uniformity.

In addition, the introduction of an array of new spinners, orbiters and plates designed to distribute the water more evenly has helped.

“People want a more uniform product and to do that you have to have more uniform water distribution,” Neibling said. “These new application devices and attention to system design is what it takes.”

A grower running a center pivot from a single pump equipped with a variable frequency drive may be able to improve uniformity on hilly ground just by relocating the pressure sensor.

Let’s say the outer end of the pivot is about 20 feet higher than the rest of the system at several points in the rotation. By moving the pressure sensor to the outer end, the grower can achieve constant water pressure in the pivot as it goes uphill and down.

“It’s not a huge complicated thing, but by doing that you have improved the uniformity of watering on that whole field,” Neibling said.

By improving application uniformity, growers may also reduce runoff, a more common problem on pivot systems than some may think.

Runoff poses an environmental concern because of the risk that nutrients or pesticides will leave the farm and make their way into other waterways. The excess water also tends to accumulate in low-lying areas – the perfect scenario for getting a pivot stuck in a flooded track. The accumulation of water in low-lying areas also can become a breeding ground for disease, Neibling said.

Cultural practices such as dammer/dike have been very effective, but there’s a limit to the amount of water they can hold, he said.

Some of the newer sprinkler packages that produce large wetted patterns up to 70 feet or more in diameter can also help, Neibling said.

“The bigger the wetted diameter, the less runoff,” he said.

—Dave Wilkins, Spudman Contributor

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