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By June 15 gasoline-powered augers will have drilled 100 holes in the corn, cotton and peanut fields of the Lower Flint River Basin in southwest Georgia. Into the holes, scientists from the University of Georgia (U.G.A.) will slip half-meter-long PVC pipes filled with sensors for soil moisture and temperature topped with a flexible antenna that can be run over by a tractor and spring back into place. Over the course of the next two years, these sensors will continuously relay soil conditions from 20, 40 and 60 centimeters deep to a computer. Combined with more accurate weather forecasts, the data will help farmers decide where and when to use their irrigation systems.
"The biggest problem we've got with irrigation is we just don't know—we use old wives' tales to decide when to irrigate," says farmer Marty Tabb, who will host the probes in a field at his 1,050-hectare Bushwater Farm near Colquitt, Ga., to help him irrigate corn, cotton and peanut crops. In addition to saving water (agriculture is responsible for 70 percent of human water use globally), the technology can also help produce more crop per drop. "Using the simplest soil monitor and a computer program, my peanut yields jumped 20 percent," Tabb reports. "I know, just from that, that if we learn how to water corn, cotton, wheat, we can save water because we tend to overwater."
Overwatering is a major problem in the Lower Flint River Basin, which lies in a region that has been gripped by drought so severe in recent years that it prompted the former governor of Georgia to pray for rain. The region produces the most peanuts and pecans in the nation, as well as vast quantities of cotton and sweet corn. And the Lower Flint River Basin is the major recharge zone for the Floridan Aquifer that supplies water to Florida, Mississippi, Alabama, Florida, South Carolina and Georgia, as well as the home of several endangered freshwater species, such as the flatwoods salamander and the oval pigtoe mussel.
Farmers in the Flint River Basin have a direct impact on this groundwater resource, because waters on the surface and belowground are directly linked: a hurricane's downpour in the area can replenish the aquifer, whereas too much pumping of underground water to irrigate fields can literally suck the water out of surface rivers and streams. "Because of the drought and because of us irrigating, we have pulled water down, and the springs along Spring Creek don't pump anymore," Tabb says of the Flint River tributary in his backyard. "You couldn't have told me that creek would ever dry, but I drove my motorcycle two miles down Spring Creek because it was so dry."
In a bid to cut down on that water use—while maintaining the more than $2 billion worth of corn, cotton, peanut and other crop production in the region—the Nature Conservancy and the U.S. Department of Agriculture, along with U.G.A. and the University of Florida, teamed with more than 1,000 local farmers starting in 2000. The partnership started by switching some irrigation systems from high pressure mists to a low pressure system that more directly mimicked rain, saving water and energy. When applying at high pressure "you lose water to wind drift and also evaporation," explains David Reckford, director of this Flint River Basin Partnership for the Conservancy. The switch to a low pressure system alone can reduce water use by more than 22 percent.