Just a few years ago, the use of satellites and global positioning systems in production agriculture may have sounded like something from a science fiction story. Today, these and other site-specific methods have pushed precision agriculture to the top of producers' priority lists, promising them more control over the productivity of their land.

“Precision agriculture is about managing the variability of your land,” says Wayne Reeves, agronomist with the USDA's Agricultural Research Service. “By doing that, producers can better manage their risks.”

Determining how to manage field variability most efficiently was the goal of Reeves and other USDA soil scientists and Auburn University researchers involved in a three-year, 20-acre, field-scale study at the E.V. Smith Research Center at Shorter, Ala.

“In previous precision agriculture studies, the initial goal was to eliminate the variability of the land,” says Joey Shaw, research team member and soil scientist at Auburn University. “Now we realize our goal is to maximize the inherent productivity of the land by decreasing inputs in poor areas and increasing them in areas that will profit the most.”

Researchers farmed half the cotton-corn rotation using a conventional system, consisting of a chisel plow, disking and no cover crops; on the other half, they used a conservation system, with year-round cover crops and no surface tillage.

Reeves says the primary objective was to integrate everything into a systems approach. “We pushed the conservation system as an entire package, with the goals being better rotation, reduced tillage, decreased compaction, increased organic matter and wise use of cover crops.”

Shaw says the first step in managing field variability is to create management zones that reflect the different landscapes.

“At E.V. Smith, we coupled high-precision elevation maps from GPS readings with soil testing data to create different zones.” He and his colleagues collected yield data using yield monitors mounted to harvesting equipment to measure crop yield and field position, and automatic steering systems with GPS on all tractors to plant cover crops, control compaction problems and allow for efficient in-row subsoiling.

By looking at the different cropping systems' interaction with the zone approach, researchers were able to match inputs to the inherent productivity of each zone. “You might increase the amendments you use in one area, such as fertilizer, lime or insecticide, and decrease them in another area,” Shaw says.

In all tests, the reduced tillage systems with cover crops out-yielded the conventional systems. “We saw benefits almost immediately, with a 14-percent increase in cotton yield and an 8-to 12-percent increase in corn yield, as well as an increase in organic matter.”

Cropping systems aren't the only agricultural domains soil where scientists are using precision farming techniques.

Researchers at the National Environmentally Sound Production Agriculture Laboratory at Tifton, Ga., are working to develop a variable rate center pivot irrigation system.

“The electronic controller at the end of the pivot uses a GPS signal to determine location,” says Stuart Pocknee, program coordinator of Advanced Technologies Research at the lab. “We change the amount of water applied by adjusting the speed at which the pivot rotates and by adjusting the individual rate of water coming out of each sprinkler.”

Pocknee believes farmers can cut costs by decreasing application to areas that require less water, such as neighbors' fields, roads and swampy areas. “From a precision farming standpoint, it makes sense to apply water where needed. Plus, the more water we can conserve, the better off we'll be in the long run.”

Researchers at E.V. Smith attribute the majority of their project's success to precision farming technologies.

Randy Raper, research team member and ag engineer at the National Soil Dynamics Laboratory at Auburn, says the automatic steering system, which provides accuracy within inches, helps increase yields. He's confident this system will be standard on tractors of the future.

“I'm not sure where a lot of precision agriculture technologies are going in terms of being useful to producers, but I'm firmly convinced the automatic steering system will be important to successful farming in the future.”

The technology doesn't come cheap: A highly accurate automatic steering system costs between $30,000 and $50,000, Raper says.

Other researchers suggest producers start with a less expensive piece of equipment. Shaw recommends yield monitors, which cost $6,000 to $8,000.

Fellow research team member Paul Mask agrees. The assistant director of Extension for agriculture, forestry and natural resources at Auburn University says, “The best tool to start with is the yield monitor because it gives you a clear picture of what's going on. Yield monitors allow you to do your own farm research and see if a new way of doing something pays off.”

Don Glenn of Hillsboro, Ala., has been precision farming since 1996 with the help of yield monitors and other precision agriculture technologies. “I'm sold on yield monitors,” he says. “I started with one and wouldn't run without it.”

Glenn believes that by giving growers concrete data, precision farming should take some the guesswork out of production agriculture.

“The best thing about precision farming is that it gives us information we didn't have earlier. Before, we might have based management decisions on a guess or a hunch. Now we have cold, hard numbers to crunch. That could be the difference between what works and what doesn't work.”