For Citrus Farms In A Drought, A Wireless System To Save Water

March 14, 2001

GAINESVILLE, Fla. — A computer-controlled irrigation system has the potential to reduce water consumption in drought-stricken Florida’s thirsty citrus farms.

The system, designed by two University of Florida agricultural engineers and a Brazilian colleague, has been tested successfully in a small orange grove at UF’s Institute of Food and Agricultural Sciences. Using microchips, wireless antennas and a central computer, it automatically varies the amount of water applied to the trees based on need, contrasting the conventional and wasteful method of giving all trees the same amount.

“This system allows different trees to be watered at different times with different amounts of water,” said John Schueller, an associate professor of mechanical engineering. “Plus, it’s completely automated, with no human intervention required.”

Schueller and Dorota Haman, a UF professor of agricultural and biological engineering, designed the system with Andre Torre-Neto, a Brazilian engineer with Embrapa, the country’s main agricultural research organization.

Installed in a grove of 208 orange trees on the UF campus, the system monitors the trees’ water needs using tensiometers, or meters in the soil that measure the amount of water available to the tree. Coupled to each tensiometer is a circuit board, which relays the measurement via a central single cable to an antenna. The antenna transmits the information to a personal computer in a nearby building. The computer processes the information and returns commands to the grove, where circuit board-equipped valves open or close and provide a designated amount of water based on its instructions.

The system is set up now to provide different amounts of water to groups of about a half-dozen trees, but it could be configured to water trees individually, the researchers say.

The test of the system comes as water use in Florida is becoming a bigger issue because of the three-year drought.

Citrus farmers are major water consumers. The state’s citrus groves consumed as much as 434 billion gallons of water in 1998, Schueller said.

Haman said when groves consist of differently sized trees, growers usually provide enough water to the large trees, which need more than the small ones. The result is a significant amount of water is wasted on the small trees.

Although water is not an expensive resource for growers now, it could become costly if the drought continues, she said. It’s also likely pollution requirements aimed at preventing fertilizer and chemicals from reaching groundwater will discourage overwatering, she said.

At $100 each, the tensiometers are too costly to be used economically for large groves, Haman said. But the price of soil moisture sensors is coming down, with at least one company working on a disposable one estimated to cost $15 to $20, she said.

That, as well as other technical improvements, should make the system a practical possibility for citrus growers.

“Sooner or later, citrus farmers and other users are going to be charged more for water,” Haman said. “This system offers one way for the industry to reduce its water consumption without adversely impacting its harvest.”