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Corn+Soybean Digest

Water With Wisdom

Until just recently, a whole field got the same amount of irrigation water. Enter new technology.

Now, water and chemical applications can be controlled in areas as small as 22' square. In fact, new center-pivot irrigation technology can pinpoint varying water and chemical needs on the go.

"For years the industry worked to get uniform water application with center-pivot systems. We managed the field for average conditions. But the rules are changing," says Gerald McNabb, Precision Irrigation Controls project manager for the J.R. Simplot Co., Pocatello, ID.

"Most standard irrigation practices waste water, fertilizer and chemicals when they're delivered to areas of a field that won't benefit from them," says McNabb. "The new paradigm is, let's make the water application non-uniform to meet the field's needs." University of Idaho engineers made a commitment to that concept several years ago and developed a precision irrigation control system.

"They realized if you can better control the water, you can better control the costs, crop yield, crop quality and non-point source pollution," says McNabb. "Simplot refined and improved the university's system and is now manufacturing it as a retrofit system for low-pressure, electric center-pivot irrigation systems."

The basics of the system are simple. But it opens almost endless opportunities for fine-tuning your irrigation management. Installation is just a matter of unscrewing the nozzles on a center pivot, adding a control valve and wiring it into the control system.

"We can control water and chemical application in zones as small as 1/100 of an acre," according to McNabb. "That's an area 22' square, or roughly the dimensions of a small house.

"On a 120-acre pivot, we can break the field down into 12,000 individual zones and make applications based on data from a computerized field map stored on a microcomputer in the control box at the pivot."

That control, of course, comes with a cost. An installed system from Simplot runs about $15,000 for a pivot.

"This really is revolutionary," points out McNabb. "The system, in effect, makes more water by using it more efficiently. Farmers are under more and more pressure to be more efficient. This system expands the capabilities of irrigation equipment and allows you to cut back on water and chemicals."

Farmers who don't use computerized field maps can gain many of the same advantages by using a computerized control panel on their center-pivot systems. The units allow you to program the system to apply water at different rates for different crops and soil types.

"It's like when you put a computer chip in anything - what it can do for you is only limited by your imagination," says Ron Friehe, who pivot-irrigates 1,500 crop acres near McCook, NE.

"The Reinke panel we use gives us all kinds of options. We use it to put on water, fertilizer, herbicides and insecticides. We just program the unit to turn the chemical pumps on and off at certain points in the field."

Friehe's automated control panel also helps him reduce electricity costs.

"Our electrical company gives us a lower rate if we agree to let them shut us down during the peak times of electricity demand," he says. "We've programmed our pivots so they turn back on when the power comes back on. There's a delay programmed in so the chemical pumps don't turn back on until the system has run at full capacity for a few minutes.

"We've found that yields have not been affected at all," Friehe says. "The time of day when it's really hot is the least efficient time to irrigate, anyway."

With 30 center pivots of potatoes, barley and alfalfa to program and monitor, Rodney Smith uses a computerized system from Dexter Fortson Associates to keep track of what's happening in the fields.

"I can sit at the computer and program a pivot to apply a herbicide with 1/2" of water for one revolution, then turn off the chemical and go right back and apply another 3/4"," says Smith, of Blanca, CO. "We have the ability to program multiple irrigation schedules and monitor them from the office, a modem or a two-way radio.

"If something goes wrong, the pivot calls us on the two-way radio and also sends an alarm to the central office and prints out all the information. With 30 pivots running, we get those calls several times a day."

In 1998, farmers will be able to separate chemicals from irrigation water with an applicator offered for the first time by Valmont Irrigation.

"Instead of using irrigation water to carry chemicals, the applicator uses an independent water source and spray boom. This isolates chemicals from the well or water supply," says Joe Goecke, Valmont's president and CEO.

"The system provides precise rate control using pulsing spray nozzles. This delivery mechanism can apply five to 10 times more carrier solution than a typical ground sprayer or aerial applicator. This enhances spray coverage on targeted weeds, insects or crop diseases."

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