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College of Food, Agricultural, and Environmental Sciences


GPS Guidance System May Replace Industry Standard

August 8, 2001

LONDON, Ohio -- The industry standard of using foam markers to accurately apply fertilizers and chemicals in the field is taking a back seat to GPS technology.

Guidance systems that use GPS (Global Positioning System) receivers are helping farmers to accurately apply chemicals or fertilizers within a six-to-10 inch distance from each application, eliminating skips, preventing overlay, and providing more even distributions. "The technology will save farmers money in wasted chemicals and also reduce driver fatigue because they won't be guessing where they should be in the field when making applications," said Matt Sullivan, an Ohio State University Extension program specialist. "I've used these systems before. They are wonderful and highly accurate. As a farmer myself, I'm ready to go out and buy one." OSU agricultural engineers are evaluating several company-made guidance systems for accuracy and overall performance. The data will be displayed at Farm Science Review, Sept. 18-20 at Molly Caren Agricultural Center in London, OH. "We've had a lot of farmers asking questions about how to use them and which ones are the best," said Sullivan. "This project is giving us the opportunity to list the advantages and disadvantages of each unit." The guidance systems have been designed to replace the foam marker system, the industry standard technique that leaves foam at various distances in the field for farmers to eyeball when applying chemicals. "Some of the booms on the equipment are 90 feet wide and if a farmer is looking 45 feet away for foam markers and trying to drive 10 MPH in a straight line, it's virtually impossible to be accurate," said Sullivan. "The guidance systems either have visual display screens or light bars that tell the farmer exactly where he needs to go. Guys are tired of looking at foam." The guidance systems also enable farmers to work in their fields at night since they aren't relying on the foam markers to guide them.

Sullivan said the cost of the systems might keep some farmers from jumping on the technology bandwagon. Prices range from $4,000 for a light bar that plugs into a cigarette lighter to a $14,000 visual display screen that can create maps to show where areas need to be sprayed, can record the time a farmer enters and leaves a field, and has an audible alarm system that signals when an area has already been sprayed. "The good thing about these systems is that they are compatible with existing GPS receivers. I've found that if a receiver has a five-hertz update rate, most guidance systems would run off of it," said Sullivan. "So if a farmer has a GPS receiver with this modification, then he may only have to spend $2,000 to get the guidance system." Sullivan said that some companies are already developing fully automatic guidance systems, that when installed on a tractor or sprayer, guide the equipment without any intervention from the driver. "It's an incredible system. The auto pilot system operates on hydraulics and the guidance system controls the hydraulic system and calculates distance using a more accurate GPS, called real-time kinematic GPS. Its accuracy is in centimeters," said Sullivan. The systems, however, are expensive, with some running as high as $50,000. "It's hard to find a use for such a system to justify spending that kind of money," said Sullivan. "I think you need big farms that can absorb that kind of cost." He speculates that less than 100 of such systems exist throughout the world. Only two Ohio farmers own one. The Farm Science Review, sponsored by Ohio State's College of Food, Agricultural, and Environmental Sciences, takes place Sept. 18-20 at the Molly Caren Agricultural Center near London, Ohio. Tickets are $6 at the gate or $4 in advance when purchased from county offices of OSU Extension or agribusinesses. Children 5 and younger are admitted free. Hours are 8 a.m. to 5 p.m., Sept. 18-19 and 8 a.m. to 4 p.m. Sept. 20.

Candace Pollock
Matt Sullivan