sealPurdue News


July 1995

Precision farming not yet ready for prime time, experts say

WEST LAFAYETTE, Ind. -- Precision farming -- the collection of technologies that is being cussed and discussed by U.S. farmers as it is proclaimed as the next agricultural revolution -- is harvesting data faster than it can be processed, say experts at Purdue University.

"The technology works," says Robert Nielsen, professor of agronomy. "Yield monitors and soil sensors produce a lot of data. It's just that right now we don't have solid agronomic underpinnings to analyze the data that's being collected. That will come. But farmers are using the technology now more out of farming intuition than out of information based on research. To actually put the data into use we have to have more research."

It's that lag that is leading some to question whether the technology will deliver as promised.

With precision farming, instead of applying fertilizer or pesticides to an entire field at a single rate, farmers test the soil and measure crop yields for small areas, and apply just the amount of chemicals that each area needs.

Agricultural experts expect the size of these areas receiving individual treatment to drop from several acres to just a few square feet several years from now, once the technique embraces technologies such as computerized field mapping, global positioning satellite technology and "on-the-fly" soil testing. (Global positioning satellite technology uses a network of military satellites to determine locations anywhere on earth to within several yards.)

An estimated 7,500 farmers in the Corn Belt already are using some form of precision farming equipment, gathering data and doing their own analyses, says agronomist Chris Johannsen, director of Purdue's Laboratory for Applications of Remote Sensing. Johannsen adds that he expects the number of farmers using the technology to remain the same for the next two or three years and then balloon as the technology becomes mainstream.

Johannsen says the best candidates for precision farming are producers who have two or three thousand acres or more. "Many of today's farmers don't completely know the history of recently acquired land," he says. "That's why they stand to gain from this technology. Somebody's grandpa may have had a hog lot in one spot out there, which is throwing off the soil chemistry, and without this technology there's no good way to spot that."

The new technology also can help spot weed problems or problems with subsurface soil compaction caused by old roads or lanes.

Despite the problems preventing precision farming from being the answer to every farmer's prayer, experts recognize that many farmers are eager to try out this new technique. They agree that the best way to begin using precision farming is to look at the end of the production process by using a yield monitor.

Johannsen says agronomists have found the yield monitors to be quite accurate. "There are farmers who start with application rates, but I recommend looking at what the crops are producing first, and then identifying problem areas," he says.

According to Mark Morgan, assistant professor of agricultural engineering, yield monitors cost approximately $3,000. They measure the amount of grain being harvested by throwing the grain against a sensor as it is sent to the bin in the combine. They take a measurement once per second, or once every seven feet at a typical combine speed of five miles per hour.

Most farmers who use the monitors use them to plot yield maps and to relate problems to the areas that have low or high yields, Morgan says. "The thing farmers need to remember is that low yield in one area isn't necessarily bad, because that may be all that area can produce. It may have reached its potential," he says.

Nielsen points out that harvesting data in the fall will not automatically bring better crops: "You have to couple this with regular and accurate crop diagnostics to explain the yield variability. The data itself tells you nothing unless you can apply understanding based on field records and notes."

Nielsen suggests that farmers monitor fields for several years before they make major changes in management. "Producers shouldn't base decisions on one ride in the combine in October watching a yield monitor," he says. "You probably need four or five years worth of data before you can make decisions, so if you're on a corn and soybean rotation you're looking at eight to 10 years of data collection."

Before investing in a yield monitor, however, Johannsen offers one additional piece of advice: "Precision farming is information-intensive and relies on computer systems," he says. "If you haven't used a computer, or you aren't comfortable with one, spend time becoming familiar with one before jumping into precision farming."

Farmers or others who are interested in learning more about precision farming and who are comfortable using computers can access Purdue's precision farming home page on the World Wide Web at

Sources: Bob Nielsen, (765) 494-4802; home: (765) 743-2973; Internet:
Chris Johannsen, (765) 494-6305; home, (765) 463-7641; Internet,
Mark Morgan, (765) 494-1180; home, (765) 589-7613; Internet,

Writer: Steve Tally, (765) 494-9809; home, (765) 463-4355; Internet,

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