Does drip irrigation really reduce water consumption?

Maybe not, says a new study.  From the New York Times:

With flood irrigation, much of the water is not used by the plants and seeps back to the source, an aquifer or a river. Drip irrigation draws less water, but almost all of it is taken up by the plants, so very little is returned. “Those aquifers are not going to get recharged,” Dr. Ward said.

Drip irrigation also generally increases crop yields, which encourages farmers to expand acreage and request the right to take even more water, thus depleting even more of it. “The indirect effect is very possibly to undermine policy attempts to reduce water consumption,” Dr. Ward said.

Policymakers, he added, must balance the need for more food and for farmers to make a living with water needs. “It’s fair to say that subsidies are very good for food security and very good for farmer income,” Dr. Ward said. “But they may be taking water away from other people.”

The Los Angeles Times’ Greenspace blog agrees:

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.”

Related discussion: Guest blogger JWT at Aguanomics starts out with a post about farm conservation versus urban conservation, and a great discussion ensues. Check it out from the Aguanomics blog: Cutting fat or muscle?

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