Cotton Farming Peanut Grower Rice Farming CornSouth Soybean South  
In This Issue
High Plains Goal: Managing Ogallala Aquifer
U.S. Cotton Prospects Strong In Vietnam
Variable Rate Irrigation: Worth Another Look
AIM For Water Conservation
It Takes Flexibility To Farm In West Texas
Editor's Note: Our Water Sources Must Be Protected
Cotton's Agenda: Arresting Resistance
Cotton Ginners Marketplace: Enrollment May Increase At Stoneville Gin School
Specialists Speaking
Industry Comments
Web Poll: In Reader Poll,
Buy-Up Bypasses CAT
My Turn: Papa’s Bell

Variable Rate Irrigation: Worth Another Look

By Carroll Smith
Senior Writer
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Variable rate irrigation (VRI) is not a new concept. However, in its infancy, the technology did have its challenges and was considered not economically feasible from many farmers’ standpoints. In plain language, the technology was not that user-friendly at the time, and it cost too much.

Today, Calvin Perry, superintendent of the University of Georgia’s C.M. Stripling Irrigation Research Park in Tifton, is excited that the main line irrigation manufacturers are now showing renewed interest in center pivot VRI technology.

For example, in early 2010, Valley Irrigation entered into an agreement with Computronics Holdings Ltd., manufacturer of the patented Farmscan Variable Rate Irrigation technology. Ac-cording to Valley, this agreement allows for the development and distribution of VRI controls through more than 460 Valley dealers worldwide. Farmscan VRI products are compatible with all Valley control panels.

Justin Wilkerson, a Valley dealer who owns J&B Irrigation in Morgan, Ga., with his brother Mark, now carries the Farmscan 7000 VRI controllers. He says the dealership will install the controller (hardware) onto the center pivot, or the farmer can do it himself. But, if the farmer chooses to install the hardware himself, he will still need technical support from a Valley dealer, Valmont or Farmscan to set up the software and get everything ready to go.

Quite A Few Improvements

Along with the controller’s more affordable price, Perry points out that VRI technology has improved from what it was in the past.

“The technology that is commercially available at the moment is the Farmscan 7000 VRI controller,” he says. “It’s easier to install, and farmers use USB memory sticks to move programs back and forth from a computer to the field. In our limited testing of this controller, its ruggedness and reliability appear to be better. Plus, you can use any ‘off the shelf’ GPS with it and not have to buy a special brand.

“This controller is an ‘add-on’ to a center pivot and uses the pressure from the main line of the pivot, so an air compressor is no longer needed as it was in the past,” Perry says. “This also helps reduce costs.”

The technology appears to be a good fit in fields with a lot of soil variability where the farmer may not be getting maximum production from the plants because they are too wet or too dry based on a normal watering method. VRI also fits well where there are several non-cropped acres in the field under a center pivot, and you want to be able to turn off the application of water and/or nitrogen in those areas.

Timing Right For SE Farmers

Although many cotton producers potentially can benefit from VRI, the technology seems to have a particularly good fit in the Southeast. Based on his experience, Perry notes that farmers in his area are becoming more aware of water, applying it more efficiently and not over watering.

“Overlapping applications in some areas can affect the growth habits of cotton causing excessive plant growth at the expense of lint production,” Perry says. “Also, farmers are becoming more interested in water conservation, especially in southwest Georgia where we are at the epicenter of the water war among Georgia, Florida and Alabama. Our producers are very politically active and proactive in managing water the best way they can by using this cutting-edge VRI technology.”

Valley Continues Field Testing

Although Computronics’ Farmscan product currently is on the market, Jake LaRue, Valley product manager, says that Valmont is making progress in simplifying VRI from an installation and maintenance standpoint.

One difference between the Farmscan 7000 series product and the Valley model that is being tested in the field at this time is that the Farmscan controller is an “add-on” to the pivot, whereas the Valley VRI uses the normal Valley Pro2 pivot panel.
“Different software is loaded into the already available control panel,” LaRue says. “So, from that standpoint, our controller is a little simpler and easier to use.”

However, LaRue also notes that when the Valley product is fully released, the company will continue its agreement to carry Farmscan because both controllers have some different characteristics that make one or the other a better value to the farmer depending on the situation. “We believe each VRI product has a place in the market,” he says.

For farmers who want to learn more about VRI, Valley Irrigation will be demonstrating its VRI product during the upcoming fall farm shows.

Contact Carroll Smith at (901) 767-4020 or


The Logistics Behind A VRI Controller

UGA’s Calvin Perry explains how the Farmscan 7000 VRI controller works with a center pivot to deliver water more efficiently.

• The Farmscan system is map-based. It allows the farmer to generate a water application map much like a fertilizer application map.

• The producer uses knowledge of the field, aerial photos, soil maps, yield maps, etc., works with the Farmscan dealer to generate a water application map in the software and usually brings in a background image to overlay the pivot definition. By that, we define the length of the pivot, where the center point is, how many zones we are dividing that field into along the main line and whether we are using every five sprinklers, 10 sprinklers or random numbers. You may have three, five or seven in different sections.

• The number of sprinklers defines how tightly you may want to control a zone as the pivot approaches a region of the field. If you want tighter control, you may use fewer sprinklers in the zone. If it is a big area, you may get by with more sprinklers.

• Set up all of that in the software, then overlay the background image of the field on the grid. Then it’s just a matter of the farmer deciding where he wants zero water or any amount between zero and 200 percent of his normal amount of water.

• 100 percent is what a producer puts out at any one time. If he wants a half-inch as his base rate, that becomes the 100 percent. If he wants 30 percent in a zone, then he gets about one-third of that half-inch.

• For the next irrigation, if an inch is his base rate, those same percentages apply. He picks a rate on the color bar on the side of the software screen and “paints” in the percentage he wants applied in different zones of the field, whether 100 percent, zero percent or anything from zero to 200 percent.

• To achieve rates greater than 100 percent, we adjust pivot speed. To put out more water in certain zones, we slow it down. We cycle sprinklers on and off to apply less water. We can combine speed control and sprinkler cycling to achieve the rate we want in any zone along the main line.

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