Are farms using water efficiently?

New research finds that California could save massive amounts of water if its farmers switched to less thirsty crops — a scenario that's not likely to happen soon, writes CalMatters water reporter Rachel Becker.

Using satellite data and artificial intelligence, researchers at UC Santa Barbara and the NASA Jet Propulsion Laboratory calculated how much water certain crops used. They discovered that by planting crops such as grains and hay instead of almonds and alfalfa, California farms could use as much as 94% less water. The study, published in Nature Communications, also found that:

Fallowing about 5% of the fields with the thirstiest crops would also cut water use by about 10%.

Farms in the southern Central Valley (such as Kern and Kings counties) used water most efficiently, while farms in the northern valley and around the Sacramento-San Joaquin Delta were the least efficient.

But whether farmers want to switch to these less thirsty, but less profitable, crops — even as climate change squeezes water supplies — is the big question. While some California farmers are experimenting with more drought-resistant crops, the agriculture and livestock industries are valued at $59 billion. The state is also known for its high-value specialty crops that can't grow easily in other environments, such as pistachios, walnuts and wine grapes.

Alexandra Biering, California Farm Bureau senior policy advocate: “At the end of the day, as a society we've left it up to farmers to decide what to grow with the resources they have based on what the market demands.”

The research found California farmers could save massive amounts of water if they planted less thirsty — but also less lucrative — crops instead of almonds, alfalfa and other water-guzzling crops, according to the research by scientists who used remote sensing and artificial intelligence.

Such a seismic shift in the nation's most productive agricultural state could cut consumption by roughly 93%, researchers with UC Santa Barbara and the NASA Jet Propulsion Laboratory reported Monday.

But Anna Boser, the study's lead author, acknowledged that replacing all of California's water-intensive crops with the least-intensive ones, such as grains and hay, is an unrealistic economic scenario.

“In reality, that is not going to happen,” Boser told CalMatters. “Grain and hay crops aren't really super economically viable in California, which is why everybody is growing crops that are more water intensive.”

In a less-extreme scenario, the researchers reported that fallowing 5% of fields with the most water-intensive crops could cut water consumption by more than 9%, according to the study, published in the journal Nature Communications. Another 10 to 11% would be saved by increasing water efficiency or by switching half of growers from the thirstiest to more average crops, the researchers reported.

“We potentially don't need to be as extreme with our changes in order to save water in agriculture as we originally thought,” Boser said.

For instance, in a critically overdrafted basin in Tulare County, that would mean switching from crops such as kiwis, walnuts, almonds, alfalfa and cherries to more average water users, such as corn or sorghum.

The market value of California's crops and livestock is estimated at $59 billion, led by dairy, grapes, cattle and almonds. The state's growers feed much of the country, as well as exporting their products internationally.

California is world-famous for its high-value specialty crops, such as pistachios, almonds, walnuts, strawberries, stone fruits and wine and table grapes. Many of these use larger amounts of water but are the least likely to be fallowed by farmers.

“Forage crops and grains are lower water use but can also be grown in many areas of the country, whereas the specialty crops California grows can't as easily,” said Alexandra Biering, senior policy advocate with the California Farm Bureau. “At the end of the day, as a society, we've left it up to farmers to decide what to grow with the resources they have, based on what the market demands.”

Climate change is squeezing water supplies, increasing temperatures and making the state's swings from dry to wet even more extreme and less predictable. Some farmers are experimenting with new crops that are more resistant to droughts or heat.

At the same time, growers are also reeling from struggling markets. Though California is the country's top walnut producer, the U.S. Department of Agriculture estimates that 25,000 acres have come out of production amid plummeting tree nut prices. And almonds, often demonized as a water guzzler, saw a drop in total acreage for the past two years.

Now, as state policies are poised to restrict the flow of groundwater from depleted aquifers, up to a million acres of prime farmland may need to come out of production in the San Joaquin Valley, according to The Public Policy Institute of California.

“In areas where groundwater pumping restrictions are in place, like in parts of Tulare County, some growers are already transitioning to lower water use crops like cotton,” Biering said. “To the extent that this study is useful for growers to understand their options under a reduced water supply, that's great.”