Technology grows affordable

11/01/2007 02:00:00 AM

Low-cost, entry-level GPS systems help producers boost efficiency

By Marni Katz

High-end global positioning auto-pilot steering systems cost half the $50,000 they once did and have become commonplace in many large-scale vegetable operations. Yet for many growers, GPS technology may still feel like a luxury that is economically out of reach.

Several manufacturers now offer entry-level GPS guidance options that will allow smaller-scale growers to get their feet wet.

“They’ve got GPS guidance systems down now that will keep you within 8 to 10 inches of accuracy that you can put on your tractor or spray rig for $1,200 or $1,500,” says Gary Prill, an Ohio State University agronomist in Van Wert and program manager for the Farm Focus farm show.

These entry-level systems may not be able to place drip tape or seed with pinpoint accuracy or allow growers to return precisely to a spot in the field days or months later. But they can help to make tillage and other operations more efficient and accurate by reducing overlaps and gaps.

“They’ve got these low-end units down in cost now to where you can’t even put a foam marker system on your sprayer for what you can buy a low-end GPS system,” Prill says. “Just in the past year or two, the price has come down enough that it is making it affordable for just about any size farmer to consider buying it.”

Prill says the systems not only help eliminate skips or overlapping, but can reduce operator fatigue because the driver follows a cab-mounted light bar screen rather than a guide row to accurately travel down the field.

Taking the GPS plunge

When grower Jerry Heilig, who farms about 1,000 acres of potatoes, sweet corn, beans and other crops near Moses Lake, Wash., purchased two new tractors this spring, he decided to take the plunge into GPS technology. He installed two steering-assisted GPS systems on his tractors for about $20,000.

On his large Case 275 tractor, Heilig installed the $3,000 EZ-Guide 500 guidance system from Trimble Navigation Ltd. of Sunnyvale, Calif., with a plug-and-play EZ-Steer steering-assistance unit. The system provides a cab-mounted road map showing where the tractor should travel. It also allows growers to map and log locations so they know where they have sprayed or disked and how many acres they’ve already covered.

Information can be downloaded to a memory stick and stored for later use. For another few thousand dollars, EZ-Steer hooks into the tractor’s steering column and provides steering assistance for traveling straight down the row once the operator has turned the rig around and lined it up at the end of each pass.

Heilig uses a free WAAS (Wide Area Augmentation System) signal to improve the accuracy so he can reduce skips and overlaps between passes. WAAS is an ubiquitous signal developed by the Federal Aviation Association for the airline industry that provides differential correction typically within 6 to 8 inches of pass-to-pass accuracy.

“We purchased the least-expensive system and put it on our tillage tractor, and it works more than adequately for what we wanted in terms of field work, chemical application, those kinds of things,” Heilig says.

On the intermediate-sized tractor that he uses for cultivation and planting, Heilig installed another EZ-Guide 500 with an upgraded OmniSTAR XP guidance signal that provides the operator with 3-inch accuracy. The OmniSTAR system costs about $3,000 more, plus an additional $800 annual subscription to get access to the international OmniSTAR satellite network.

Heilig used that system this year to plant beans and also says he will use it to shape beds and plant and cultivate potatoes next spring.

“That unit worked remarkably well,” he says. “I was extremely pleased with it. I’ve got one circle that has a corner on a hillside and it literally laid those rows in there perfectly.

“Before we had to do it by hand, which—depending on the capability of your applicator or tractor operator—would determine how accurate your planting would be. The GPS system certainly exceeded what we could do, and our guess row accuracy before was actually very, very good.”

The system Heilig purchased is about $10,000 to $15,000 less than the most expensive one.

High-end versus low-end systems

The difference between the more expensive GPS systems and the entry-level ones is the accuracy of the type of signal they receive, says Steve Gilbert, manager of GPS dealer Ag Tech Services in Moses Lake.

Satellite signals used in GPS must be corrected as they come through the atmosphere. Ubiquitous signals, such as WAAS, are free but only provide accuracy within 6 to 12 inches.

The most expensive RTK (real-time kinematic) signal can let a grower turn on a dime but requires a significant investment. Growers must install a $13,000 base station near their fields or subscribe for $1,000 annually to a signal triangulation service provider.

For growers laying drip tape or other work requiring pinpoint accuracy, that investment may be worth the price, Gilbert says.

But for the vegetable grower just looking to dip his or her toe into the technology pool, he says the low-cost GPS light bar systems using free sub-meter GPS signals will help tractor operators reduce skips or overlaps in the field, reduce passes and save on inputs and labor.

“For $5,000 to $6,000, a grower can pull an EZ-Steer system out of the box and be good to go,” Gilbert says. 

He estimates that even the basic GPS system can save a grower several days on his tillage by eliminating up to 10 acres of overlap on a typical 130-acre center-pivot-irrigated field.

The systems also can be upgraded if growers want to obtain better accuracy, Gilbert says.

Like many new technologies, Heilig says it’s hard to determine the exact return on investment, but he knows that GPS is making his operation more efficient and more cost effective.

“The advantage with planting is that you utilize your acreage more efficiently, which probably would improve your yield, especially if you have a tendency to get wide guess rows,” Heilig says. “If nothing else, it’s a pride thing if somebody else drives by and sees your lines nice and straight.”

To receive this article, as well as all of the articles in the November 2007 issue, subscribe to the print version of The Grower magazine.

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