CHAMPAIGN, Ill. -- Illinois farming is going high-tech. Come this spring, a growing number of farmers will use computers linked to global positioning satellites to apply fertilizers and pesticides to their fields. Then in fall, they'll use GPS technology to monitor their harvest yields.
"GPS and site-specific farming have become part of the vocabulary of corn and soybean farmers," said Eric A. DeVuyst, an agricultural economist at the University of Illinois. GPS refers to the network of 24 satellites that, orbiting 11,000 miles above Earth, can pinpoint the location of a moving vehicle by means of a receiver in the cab.
Global positioning can give precise readouts of field and crop boundaries, within an accuracy of 3 feet or less, once certain adjustments are made. The U.S. Department of Defense, which launched the satellites for military purposes, has placed intentional errors in the transmissions (to ward off terrorists); atmospheric changes can further distort accuracy. However, farmers and other civilian users may set up ground receivers to correct the inaccuracies.
Linked to field sensors on combines, farmers use GPS technology to develop computerized maps for soil moisture, crop yields and other information. "A computer reads the stored soil and fertility maps to determine the desired treatment rate, and the application rate is adjusted accordingly," DeVuyst said.
At present, the technology is used mostly for applying fertilizer and lime to fields. But DeVuyst says it is only a matter of time before pest infestations can be mapped with hand-held computers linked to a GPS receiver, allowing site-specific treatment in the next growing season.
Cost is a major hurdle of GPS technology, says John F. Reid, a U. of I. agricultural engineer. "The price for GPS receivers and related units currently range from $3,000 to $30,000 depending on the accuracy and capabilities of the instruments," Reid said. "That adds a lot to the current $150,000 to $180,000 selling price of a new combine." Nevertheless, one out of four combines sold last year were equipped with GPS yield-monitoring units, he said.
U. of I. engineers, meanwhile, are taking GPS to its next step -- as a guidance system for tractors, combines, spray rigs and other moving equipment. A research team led by graduate student Timothy Stombaugh is developing a system in which vehicles can be steered along a crop row by means of satellite navigation.
"We don't envision GPS taking the place of the farmer in the cab," Stombaugh said. "This would pose serious safety and liability questions, among other things. But it could let farmers do their field work more efficiently."
What's more, the new technology is expected to aid the environment by lowering chemical runoff from excess doses of pesticides and fertilizers and by reducing soil erosion.