To passersby, the fields of Colorado's eastern plains are a vision of uniformity. Mile after mile of pinstripe rows of corn, sugar beets, and onion stretch monotonously toward a hazy, green horizon.
To the farmers who tend these crops, however, the view is very different. Looking down from their combines, growers like Elmer and Larry Rothe see a diverse landscape: oases where sugar beets flourish, islands where corn stalks are sparse.
For years, farmers like the Rothes have largely accepted these variables, applying fertilizers, bug sprays, weed killers, and water to make the whole field prosper.
Today, with the help of navigation satellites developed by the military to guide fighter planes, the Rothes now apply fertilizer strategically, where it's most needed.
"It looks real good, real even growth," says Elmer Rothe, standing in a field of sugar beets. In most years, he says, the field would be a patchwork of light and dark greens. This summer, with precision doses of fertilizers, it's uniformly lush. "But come back when it's time to harvest. Then we'll see."
As military satellites increasingly become open to public use, farmers are able to draw detailed field maps that depict fertility, aridity or soil-type of patches as small as 10 feet across.
When satellites are used in tandem with high-tech yield monitors - which tally a crop as it rushes through the combine - farmers can know exactly how much they're producing at any point along their rows.
This practice is known as "precision" or "site-specific" farming because it allows farmers to micromanage large acreages. According to its proponents, this growing field promises a host of economic and environmental boons.
By applying chemicals where they're most needed - and sparing fertile, pest-free zones - farmers can increase yields and save money, they say. Such strategic targeting may also reduce the collateral damage associated with fertilizers such as nitrogen, which leaches rapidly into the water table.
Perhaps more important, say boosters of precision, this new technology arms farmers with accurate feedback on the condition and output of their management practices.
"What we're really doing is transforming the farming arts into farming sciences," says Rob Monson, president of Minnesota's AgChem, which now makes chemical applicators that distribute chemicals in precise doses as they rumble across the field.
By taking the guesswork out of farming, precision agriculture stands to revolutionize food production, say proponents, who often compare the advent of "information farming" to the invention of the tractor.
Still, even the most ardent enthusiasts admit much is still unproved. "Right now, there's not enough raw data to be precise about the results," says Pierre Robert, director of the Precision Agriculture Center at the University of Minnesota. "It will take some more years to get that data," Dr. Roberts adds. "But that's OK. When farmers switched from horses to tractors it took years before they really used the new tools efficiently."
Still many farm suppliers are not waiting for absolute proof before leaping into what could be a multibillion-dollar industry. Wisconsin's Case Corp, and Illinois's Deere & Co., for example, now offer yield monitors and satellite guidance as standard fare on tractors and combines. Defense contractors, meanwhile, are using their expertise with satellite tracking to develop their own precision farming systems. For its part, AgChem recently teamed up with Lockheed on a precision mapping program.
Elsewhere around the country, private and public agronomy labs are experimenting with a host of futuristic farm implements: Ground-penetrating radar is being used to determine soil types, automated sprinklers apply precise showers on thirsty plants, while infrared plane-mounted video cameras monitor weed and crop growth.
Though experts think less than 5 percent of America's farmers are using precision techniques, there's considerable evidence of growth. Conferences on precision agriculture are sprouting up across the country, while smaller farm supply companies are also getting involved.
"What's nice about this stuff is that it's pretty simple and not too expensive," says Can Weins of Centennial Ag, a Colorado farm supplier. Along with his partner, agronomist Bill Gilbert, Mr. Weins has been providing farmers with precise soil maps, which are then stored in a computer.
The computer is hooked to a fertilizer rig equipped with a satellite navigation receiver. As the tractor chugs across the field, the receiver tells the computer exactly where it is and the computer then tells the fertilizer dispensers exactly what to spray when.
Such systems have proved successful for Midwestern sugar beet and potato growers who have reported yield increases worth $50 to $90 per acre. Still, not everyone's shouting, "Eureka!"
"I've got hundreds of those pretty pictures and right now they're worth about as much as the pictures hanging on your wall," says John Hess, an Idaho farmer who's been working with government scientists on his fields. "We laid the yield maps on top of the nutrient maps and found no correlation whatsoever," Mr. Hess says. "Some areas with the lowest nutrient availability are some of the places with the highest yields."
And therein lies the rub of precision agriculture. Were Hess's discrepancies caused by variations in the farm's microclimate, or was Hess simply driving his combine too quickly over the field?
Many questions remain unresolved. Environmentalists and proponents of "sustainable" and organic growing worry that precision farming will divert needed research funds from less chemical-intensive growing methods. They also question whether precision necessarily reduces pollution. A spot of sandy soil, for example, might need more nitrogen to be productive. But those coarse grains may also let that nitrogen flush more quickly into the water table than fertile earth would.
Still, some say sustainable and precision agricultures are not necessarily at odds. After all, precision farming does not have to be chemical-laden or high tech. By most definitions, in fact, the average backyard gardener gets comfortably into this evolving paradigm. Still, some, like Idaho's, Hess are cautious: "Farming is still 85 percent art," he says.