Wired
by Danielle Venton
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California’s Central Valley farmers have a problem. Agriculture accounts for about 80 percent of the state’s water consumption, and in the midst of a historic drought, it is the largest potential source of water savings. Farmers want to be good stewards of the land by helping save water—it is, after all, what sustains them. But there’s a limit to what they can eke out of the soil with the water governor Jerry Brown has given them to work with.
Or maybe there isn’t. New irrigation techniques have made it possible to increase yields with less water than farmers once thought they needed. It’s even possible to farm essentially without water—growing produce by using the water and fertilizing nutrients already in the soil.
In Templeton, California, Mary Morwood Hart is using dry farming on her Grenache, Mourvedre, and olive trees, carefully cultivating the soil on her 20 acres so it can sustain growth without water. Over the past century, US agriculture has pushed itself to produce higher and higher yields by carefully engineering its plots: building larger farms with more advanced mechanics and increasing reliance on fertilizers, weedkillers, and pesticides. That’s brought more food to market. But it’s also depleted the soil—those steps tend to kill the microbes that build organic material and make it sponge-like.
Hart and other dry farmers think they can find a solution in the dirt itself. When soil is left to its own devices, it becomes rich in organic material. It loses less water to runoff and evaporation, and food can grow with little or no irrigation.
That’s especially true of grapes. Hart and her husband, who run the farm together, believe dry farming prolongs the vine’s life, and their method isn’t exactly devoid of moisture: The calcareous clay soils in Templeton, she says, hold a lot of water. “It creates a situation where the tap roots have to dig deep down into the soil to find moisture and it brings about character and a complexity of flavor,” says Hart. “When you do irrigate a vine, the roots tend to grow very close to the surface, because they’re just waiting there for their drops of water.”
The downsides are what you might expect: Dry-farming reduces the weight of the grapes, so the farm’s overall output is lower than average (typical output is four to six tons per acre, while Hart gets a measly 1.3 tons). But without irrigation, her plots are less expensive to tend to and easier to grow on hillsides. And old vines and the smaller grapes that grow on them are prized for their flavor—which she can charge a premium for.
At Molino Creek Farms on the Central Coast, grower Joe Curry raises dry-farmed tomatoes on 136 acres. He and the other farm founders chose dry farming because their land has very little access to water. Once his tomatoes are taken out of the greenhouse and planted in rows, they receive no additional irrigation. That’s only possible, he says, because the farm takes care of the soil. Prior to planting they mow cover crops, leaving them on the ground to decompose. The nutrients re-enter the soil, used to support the next season of growth.
The effect on water usage is dramatic. According to the National Resource Conservation Service, an arm of the US Department of Agriculture, increasing soil organic content in an acre of farmland by just 1 percent can save up to 27,000 gallons of water. (Other estimates are less hefty, but still impressive.)
But waterless agriculture isn’t the answer for everyone. Tomatoes, grapes and vegetables are relatively high-value crops—not all farmers can afford sacrificing their high yields for higher quality. And certain crops like lettuce would taste terribly bitter if dry farmed. So other farmers have turned to other methods to conserve water.
Irrigation options
Traditionally, most Californian farmers have used flood irrigation on their plots—which made sense, because that’s how the Central Valley once functioned on its own. “The Central Valley used to be wetlands,” says Ken Dickerson of the Ecological Farming Association. “Its role was to absorb water coming down from the Sierra Nevadas and let it sink into the ground.”
That means flood irrigation can be good, because it gives the land the opportunity to recharge its groundwater reserves. (Those very same resources have been so overdrawn in recent years that the valley is noticeably sinking.) But it’s also wasteful in a drought, especially when farmers use it for coastal row crops like lettuce or broccoli, which don’t grow in the former wetlands areas. And it can wash gross stuff like fertilizers and pesticides into groundwater and streams.
So with mandatory cutbacks being enforced by the state, farmers who can’t give up water entirely are stepping away from flood irrigation to embrace sprinklers or drip systems, which use tubes with pinholes that deposit mere drops of water at the base of plants, where it’s needed. Many almond growers—California’s favorite drought scapegoat—now use micro emitters of water instead of flood irrigation, along with many large-scale vegetable growers in the Salinas valley.
Kent Hibino has been farming vegetables at Henry Hibino Farms in the valley since 1995. He’s seen big changes in the past decade using drip irrigation. Yields are better per unit of water. And his pesticide spraying costs are down, because watering at the roots has reduced problems with mildew.
Farmers also can be more scientific about when and where they apply water. Cutting back on watering during drought-tolerant growth stages can save water and improve crop quality or yield. Adopting these steps could save 6 million acre-feet during a dry year, according to a study by the Pacific Institute. And some farmers are increasing on-farm storage—adding additional ponds as reservoirs.
Another option might be to replace water-guzzling crops with those that don’t need much water. So far, when farmers have cut back on irrigated acres, they’ve gotten rid of field crops like rice, cotton, hay, and corn silage—things more easily grown in other parts of the country. But farmers can’t deny the reality of California’s agriculture economics: They’ll continue grow what consumers will pay them to grow. Any interest in prickly pear cactus, carob, or saltbush anyone? Didn’t think so.
By and large, then, the state continues to pump out water-hungry crops like almonds, walnuts, raspberries and asparagus. Farming is core to California’s sense of itself—and to its economy. Agriculture employs about 3 percent of the state’s workforce and counts for about 2 percent of the state’s gross domestic product. And other economic sectors, not counted in the two percent, are propped up by food growing: trade, manufacturing, tourism, food service.
“The consumer wants these products, and California is one of the few states that can produce them nine months out of the year,” says Michael Cahn of the University of California’s Cooperative Extension in Monterey. “The growers wouldn’t be doing this if there wasn’t a demand.”
In the long-term, California must continue being inventive in keeping its land resilient to drought. Some solutions go beyond individual farmers’ choices. During the winter rains, a lot of freshwater flows to the ocean—some of that could be diverted and stored in the ground. Farmers also could start using municipally recycled water (a project in the Salinas Valley is currently underway). “It’s not cheap,” Cahn says. “It’s still a few hundred dollars per acre foot, but it shouldn’t be wasted, right?”
Other countries, in much more dire water situations than California, are able to maintain thriving agricultural systems this way. “My friends in Israel get two uses out of every drop,” he says. “They tell me ‘One day, you’ll be just like us.’”
One day, that may very well be true.
