LOS ANGELES — Seventy-six years after the invention of the modern sprinkler helped revolutionize farming, a professor of environmental engineering is pointing a laser beam across an alfalfa crop in Southern California's Imperial Valley, looking for a better way to conserve the millions of gallons of water sprayed each year on thirsty crops.
Jan Kleissl and a handful of his students at UC San Diego have rigged up a contraption called a large aperture scintillometer to study exactly how much irrigation water is lost to evaporation and the peak times that water disappears.
The hope is to give farmers a more accurate, up-to-date reading of how efficiently their crops are using water than current technology allows.
"What's new about our approach is the monitoring side of it," Kleissl said by phone from his office. "We're trying to improve on that."
Some advances in irrigation have focused on the water delivery system -- such as Southern California grower Orton Englehart's 1932 invention of the horizontal action impact drive sprinkler, which he patented the following year.
But although most farmers are experts at managing their irrigation by sight, recent years' droughts have called for more sophisticated ways to use -- and save -- water.
Water became an even more valuable commodity in California last year, when a federal judge ordered federal and state agencies to restrict pumping in the Sacramento-San Joaquin River Delta to protect the threatened delta smelt, severely cutting the growers' supply.
Further restrictions could result from the recent decision by state fish and wildlife managers to limit pumping to protect another native fish, the longfin smelt.
These shortages are prompting researchers to devise new ways to determine when to irrigate and how much water to use, said Khaled Bali, an irrigation expert for the University of California Cooperative Extension office in Imperial County. "There's not enough water to go around," he said.
San Diego County farmer Bob Polito, who was forced to remove 10 of his 60 acres of citrus and avocado trees from production after last year's pumping restrictions, said high-tech irrigation aids have so far been too expensive. But he said the increasing scarcity of water may force him to invest in technology to monitor his trees' water efficiency.
"Anything that gives you an accurate accounting on that score would be a help to farmers," Polito said.
