By Brad Haire
University of Georgia

The scientists will use a three-year, $500,000 Natural Resource Conservation Service grant to install on farms and conduct field days for variable-rate irrigation systems.

Five center-pivot irrigation systems in Georgia and one in South Carolina will be retrofitted with VRI technology each year for the next three years, said Calvin Perry, a researcher with the UGA College of Agricultural and Environmental Sciences.

"The goal of this project is to take an innovative product like VRI to farmers," said Perry, who is also an engineer with the UGA department of biological and agricultural engineering, "and let them test it and see it working and get them interested in using it."

Crops have to have water from rain or irrigation to grow properly. The center pivot is commonly used for irrigation in Georgia.

A center pivot is a pipe that can be as long as several football fields. It's attached to a water pump in the center or at the edge of a field. Small nozzle sprayers dangle from the pipe, which can stand 15 feet above the ground. It's supported by triangular steel ribs on wheels. The entire system pivots in a full or half circle in the field.

Farmers don't have much control over how much water the nozzles spray as they pass over crops like peanuts, cotton or corn.

Fields, even small ones, can vary widely in topography and soil types. Some places can be wetter or drier than other places in the same field.

The concept behind VRI technology is simple: Apply water when and where crops need it. Don't apply it where they don't. VRI technology uses computer maps, sensors and software to control where and how much water the nozzles on a center pivot spray on crops.

The VRI technology for this project was developed at UGA's National Environmentally Sound Production Agriculture Laboratory in Tifton, Ga. UGA is in the process of getting a patent for the technology, Perry said.

UGA scientists have tested the water efficiency of VRI systems on one farmer-owned field in east Georgia and two in south Georgia. The VRI systems allowed the farmers to place the right amount of water on their crops for optimal yields and reduce the water used by 8 percent to 20 percent in each year.

"In most cases," Perry said, "VRI conserves water."

There are about 10,000 center pivots in Georgia, said Kerry Harrison, an irrigation specialist with the UGA Extension Service. They're used to water about 75 percent of Georgia's 1.5 million acres of irrigated cropland.

The grant funds will be used to identify VRI-suitable pivots in Georgia and South Carolina, Perry said. Web sites and other educational materials will be created to inform and educate stakeholders and policymakers in both states on VRI systems' benefits for communities.

To find out more about VRI, call (229) 386-3377. Or go to the Web site (www.nespal.org/vri).