Efforts to reduce water use in agriculture could end up having the opposite effect

Johns Hopkins expert urges evidence-based approach to environmental programs

Paul Ferraro

Image caption: Paul Ferraro

Image credit: Will Kirk / Johns Hopkins University

Steps designed to increase water efficiency in domestic agriculture could, in fact, result in more water use, Johns Hopkins University's environmental economist Paul Ferraro writes in a commentary published today by Bloomberg View.

Ferraro—a Bloomberg Distinguished Professor in JHU's Carey Business School and Whiting School of Engineering and co-director of the Center for Behavioral and Experimental Agri-Environmental Research—focuses his research on determining whether conservation technologies or measures really work.

"Environmental problems are largely human behavior problems," Ferraro told JHU Engineering magazine recently. "They aren't biological or chemical problems. The key that's often missing is an understanding of human behavior. Why is someone behaving in a way that damages the environment?"

Case in point, he writes for Bloomberg View—the nearly $50 million pledged recently by the U.S. Interior and Agriculture departments for water conservation efforts. While this seems like a positive step, Ferraro notes that "the assumption that such spending automatically leads to reduced water use is not grounded in theory or evidence. In fact, improving efficiency may fail to deliver large water savings and even, paradoxically, increase use."

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A study by Cynthia Lin of the University of California at Davis and Lisa Pfeiffer of the National Oceanographic and Atmospheric Administration looked at how farmers in the Ogallala aquifer of the Great Plains changed their water use after being subsidized to adopt more efficient irrigation technology—drop nozzles, which deliver water from just above the crop to decrease evaporation. The Ogallala aquifer is one of the largest in the world, but it is being rapidly depleted, and more than 90 percent of its pumped water goes to agriculture. Unlike previous studies, Lin and Pfeiffer collected water-use data to isolate the causal impacts of the new nozzles.

The results were striking. Rather than finding that farmers who used drop nozzles reduced their water use, they showed that those farms increased their consumption, on average, by about 3 percent. The efficient technology had an effect, but it was the opposite of what was intended.

Why did this happen? When water delivery becomes more efficient, using more water can increase profits. Farmers may also feel less obligated to conserve water because they have done a good deed by adopting the technology. (Psychologists call this a "licensing effect.") In the Ogallala, some farmers responded to the new technology by increasing how much land they irrigated or switching to more water-intensive crops—from wheat to corn or soy, for example.

Ultimately, Ferraro advocates for an evidence-based approach to environmental programs.

"In medicine, where the guiding ethic is to do no harm, new ideas are rigorously tested in the field before being scaled up," he writes. "A similar culture of rigorous field evaluations could transform agricultural and environmental science."

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