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Farming with drip irrigation consumes more water

November 18, 2008 |  5:39 pm

Lowell Weeks in his Coachella Valley grove

It's the opposite of conventional wisdom: When farmers use drip irrigation on their crops, they wind up consuming more water than if they used less efficient irrigation techniques. At least that's what water resources professor Frank A. Ward concludes in a new study.

Ward, who is on the faculty of New Mexico State University, used computer models to analyze farm water use in the upper Rio Grande River basin.

While drip irrigation can require half the water that flood irrigation does, plants absorb more water with drip, crop yield increases and more water is lost to evapotranspiration. Because drip is more efficient, there is also less overflow to seep back into aquifers or wash into nearby streams or rivers.

That means less water for downstream users and future generations dependent on the aquifers. "Higher consumption comes from someplace -- someone else's use," Ward said. Drip, he added, has its benefits. "It's just not a water conserving thing."

To get a true picture of water use and more equitably administer water rights, Ward suggests it should be measured according to how much is depleted from a basin, not by how much comes out of an irrigation pump.

The study, published this week by the Proceedings of the National Academy of Sciences, was co-written by Manuel Pulido-Velazquez of the Polytechnic University of Valencia in Spain.

-- Bettina Boxall

Photo: Lowell Weeks in his Coachella Valley lemon grove, which uses drip irrigation. Credit: Gina Ferazzi / Los Angeles Times

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