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Cornering GPS

Prototypes of GPS-guided irrigators are achieving pinpoint accuracy.

Dreamers in the center pivot irrigation business are forever trying to design a fully automated rig. Manufacturers and researchers in the industry have been after full automation as if it were the Holy Grail.

You may remember seedigation, which really didn't catch on, and chemigation and fertigation, which did. Then there was automated watering based on "communication" between ground moisture sensors or leaf monitors and computer-driven center pivot systems.

So it comes as no surprise that manufacturers and researchers alike have their eye on GPS technology.

Prototype stage. In 1995 Dale Heermann and fellow researchers with the USDA-ARS in Fort Collins, CO, found that GPS receivers mounted at the pivot tower could provide position accuracy comparable to that of buried wire. This paves the path toward identifying exact field position with computerized mapping technology that, in turn, can vary the rate of application - on a per-nozzle basis - of water, chemicals and nutrients to plants in specific parts of the field.

"It's just a matter of time," says Charles Meis, vice president of engineering for Lindsay Manufacturing. His company has a prototype GPS guidance system for selected Zimmatic irrigation units that will provide circle-like accuracy and convenience on corner systems and lateral move systems.

"We had a prototype out last year, and this year we are going into the field with 10 more. We plan to have a product we can retrofit on our more recent machines," Meis says. He hopes to be at that point within two years.

Al Sawtelle, project manager for Valmont Industries, says his company also is in the hunt for GPS cornering systems. "We're far enough along that we would feel safe putting them into the marketplace," he says. "The technology is extremely accurate - within 4 to 6 in. of ground zero. However, it is unlikely that it will be cost-effective in the near future, not with $2 corn. Unless we can provide a product that can either add value or create enough savings for a payback, it doesn't pay to introduce GPS technology to the market."

Four-inch accuracy. At Lindsay, Meis says GPS offers just the accuracy and automation potential the company was looking for. However, he is bothered by one hang-up that occurs when the corner unit is turned on. There is about a 20-min. delay as the computer looks for the constellation of satellites and starts processing data. "I don't know if farmers have that kind of patience. This summer we would like to get that time down. That may not be possible," Meis admits.

He says Lindsay recruited a company to bring in the GPS technology with the understanding that the contract would be fulfilled only if the corner system was accurate to within 8 in. "We ran the system 20 hrs., back and forth over 1,500 ft., and it was within 4 in. They got their check," he says.

Saving input dollars. The corner systems may provide the same precision farming possibilities as field mapping and apply water and chemigation as accurately as the main system. They also may offer the guidance of steerable corner arms that can cover up to 14% more acres. Meis sees a good economic fit for GPS guidance initially in applications where farmers are using buried guidance systems and in the rocky terrain where such guidance systems cannot be buried. "Gophers can't eat a GPS," he quips.

The big payback will come, however, when the technology will help drive input savings.

"The time is coming for this kind of technology," Meis declares. "As farms become larger with fewer operators, we'll see even more dependence on this sort of automation, but now with GPS we'll add the accuracy."

"Accuracy is the key," Meis continues. "Those fertilizer and custom applicators can cross a field at 20 mph and be within 40 ft. and be okay. I've got to do the same within a foot. And with this prototype, I can get to within 4 in. You tie that down with our systems that allow our growers to preprogram their irrigation programs and to remotely control and operate multiple systems, and it all comes together," he says.

For more information, contact Lindsay Mfg. Co., Dept. FIN, Box 156, Lindsay, NE 68644, 800/829-5300 or circle 205; or Valmont Industries, Dept. FIN, Box 358, Valley, NE 68064, 800/825-6668.

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