High-tech fattens the bottom line

Agricultural Research, April, 1996 by J. Kim Kaplan, Dennis Senft, Don Comis, Jill Lee

Henry Hagenbuch, who farms soybeans and corn with his brother in north-central Illinois, figures that he will offset the costs of precision farming, including buying a yield monitor, in 2 to 4 years.

"We've only looked at the numbers crudely, but that's how it comes out. With 1,100 acres, a small improvement per acre can pay off quickly," Hagenbuch says.

He began keeping accounting records for his farm on a computer in 1983, and today he looks at marketing data by computer at least weekly. Hagenbuch purchased a yield monitor 2 years ago and so far has had about half of his soil tested as part of precision farming.

"I was amazed to find pH's [soil acidity] below 6 and above 7 in the same field. It certainly changed the way I have lime put down," he says.

However farmers get their mountain of information, it has turned their winters into a season of planning rather than rest. With exact yield data in hand, farmers go back and figure out why harvests were lower in some spots than in others.

Automating Irrigation

One of the biggest advantages that computers can provide is information on what is actually happening to crops right this minute - not what the farmer thinks might be happening, or what it looks like might be happening.

For example, within a few years, a cotton farmer in Lubbock, Texas, might finish lunch and then run a quick check for a flashing red light on the office computer console.

"I know it's been hot for the past few days; the plants are thirsty now," the farmer mutters and reaches for a glass of iced tea, content that the computer has turned the irrigation pumps on.

Had that cotton farmer driven out to the fields in the hot afternoon, the same red lights would have been flashing on a center-pivot irrigation pipe as it watered crops in a giant circle. What the farmer would not have seen is the infrared signal that the plants were sending to flashlight-sized thermometers mounted on the irrigation arm.

The invisible infrared signal is used to take the temperature of cotton leaves every 6 seconds around the clock. The warning lights came on because the cotton showed a temperature of more than 82 [degrees] F for more than 4-1/2 hours - a combination that spells a need for water.

With this computer-controlled equipment, irrigation takes place only when there is hard evidence of the plants' need for water.

The system is based on a concept discovered by ARS scientist Dan Upchurch and colleagues Don Wanjura, John Burke, and James Mahan at the USDA-ARS Plant Stress and Water Conservation Research Unit in Lubbock.

Plants need water both for growth and to remain cool. Each crop has a preferred temperature range at which it grows best, called the thermal kinetic window.

There is also, for every location, a certain amount of time that the weather causes even a well-watered plant to be above its optimum temperature. This is called a site-specific time threshold.

As the system is envisioned, farmers would control their automated irrigation systems with a computer cartridge containing both the thermal kinetic window and time threshold for each crop. Prototypes have already been built, and the scientists have recently signed a cooperative research and development agreement, in hopes of bringing a farm-size version to market.