A better way to water. (Innovative Technologies).

Two years ago, the death of trees at Florida's 2,500-acre Flatford Swamp sparked an investigation by the Southwest Florida Water Management District, which concluded that the trees were drowning. "From March to May, there should be very little water in the swamp," says David Tomasko, a senior environmental scientist with the district, "but it has stayed wet for the entire dry season for ten to fifteen years now."

Irrigation, while necessary, is the source of about 12-15 million gallons of extra water that enters the swamp each day; the occasional rains that fall during the dry growing season can inundate fields, causing subsurface water to seep into nearby swamps. To restore the swamp, the district is sponsoring projects to reduce movement of irrigation water off-site. One project is paying half the cost to redirect swampbound water back to irrigation systems on about 1,600 acres of farmland. A second project is testing whether an innovative irrigation system known as fully enclosed seepage can reduce seepage in the first place.

Fully enclosed seepage is a relatively new irrigation method, says Ronald Cohen, project manager for the district. The system uses drip irrigation equipment pioneered in Israel. Among its advantages are better control of how much water is applied, which seems to improve crop yields, says Cohen. "The closer you are to the roots and the more uniform the water supply, the better."

In conventional irrigation, water flows down open ditches between crop rows, often saturating the entire upper layers of soil. The new technique, developed with the help of Craig Stanley, a researcher at the University of Florida's Gulf Coast Research and Education Center, uses buried drip irrigation pipes to inject water about 24 inches under the ground. The water drips to an impenetrable hardpan about three feet below ground, which holds the water for take-up by plant roots. By keeping the upper soil layers drier, more rain can be stored, Cohen says, which reduces runoff during heavy rains. He says the system is well suited to southwest Florida's unique farming situation, with its shallow water table.

Because wet fields foster fungus, the system also promises to reduce fungal disease, says Gary Bethune, director of engineering at Pacific Tomato Growers in Palmetto, Florida. In 2001 Pacific Tomato completed a three-year test of fully enclosed seepage irrigation on about 50 acres of tomato fields adjacent to Flatford Swamp. The technique used only two-thirds as much water as previous irrigation techniques, says Bethune. "It hit a home run in water conservation." Given Florida's falling water levels in aquifers and soaring state population (16.8% growth in the 1990s versus 9.8% for the United States as a whole), he says, "that's a motive of tremendous importance."

At $800 per acre, the subsurface system still costs more to install than conventional irrigation ($500 per acre). "There are less expensive ways to irrigate crops, but they are not as water-conserving," Bethune says. He also fears that farmers may eventually be forced to compete with city residents for water: "The owners of Pacific Tomato ... realize that the future is one of water conservation, that the company needs to be moving in that direction." He says the company plans to install fully enclosed seepage irrigation on 500 additional acres by fall 2002 at its own expense.