California’s freshwater supply is evaporating; a UC Davis farm explores solutions
About 7 miles west of UC Davis sits Russell Ranch, a 1,500-acre sustainable farm that studies long-term issues affecting California agriculture. One issue near the top of the list: water.
“This institute exists to be forward-looking on big issues,” explained professor Tom Tomich in his opening remarks at last month’s Field Day, an annual ranch tour attended by researchers, students and local growers. Tomich, also director of the Agricultural Sustainability Institute, which oversees Russell Ranch and other university sustainability projects, says that “water is the No. 1 or No. 2 issue among [agriculture] stakeholders.”
Field Day presentations focused on a number of additional pressing research issues as well: dwindling bee populations, the efficacy of organic pesticides, employing biochar as fertilizer. But as ranch staff and university researchers lead visitors through fields of tomatoes and corn, one urgent theme resurfaced throughout the day: California’s evaporating freshwater supply—and what the ranch is doing about it.
The ranch explores and evaluates the impact of water use by implementing drip-irrigation systems in some crops. Three researchers presented the results of using drip-irrigation systems on tomato fields, which showed that the drip method produced greater crop yields and, all in all, resulted in a 30 percent increase in water-use efficiency.
But drip irrigation got mixed reviews during a growers’ panel later that day. Growers John Meek and Rick Martinez reported that drip lines helped increase crop yields and decrease pesticide use. Grower Scott Park, though, abandoned drip irrigation on his farm after gophers kept chewing up the plastic lines and algae and minerals gummed up the system, requiring weekly flushes.
Another water system discussed during Field Day was the ranch’s irrigation system, which employs two pumps and a reservoir.
Currently, Russell Ranch relies on the reservoir for storing water, which, according to a fact sheet provided to SN&R, loses 500 gallons per minute due to seepage into the surrounding soil. The reservoir loses nearly 20 percent of its volume per day.
Ranch staff considered one water-saving option: lining the reservoir. But while the lining would stop the water seepage, the $60,000 cost was a hefty chunk of change.
Soon, another option presented itself: installing a new pump system, featuring a variable-frequency drive, which would allow staff to better control the flow of water and eliminate the need for a reservoir altogether.
And the new pump system will save more than water. With pumping time estimated to drop from the current six days a week to five, Russell Ranch will shave off some 400 hours of pumping time, resulting in about $27,000 in electricity savings per year. The pump system will pay for itself in less than three years.
The ranch maximizes its water-use efficiency through a satellite weather system. Weather stations spread across the property measure heat, wind and other variables to calculate exactly how much water actually is lost each day.
Another set of experiments explored the use of cover crops to reduce soil runoff and nutrient loss. The studies showed that cover crops increase water infiltration, meaning less water is lost to runoff.
Overall, Russell Ranch explores the growing issue of water conservation as it relates to the issue of ever-decreasing availability. And by decreasing its water use—and teaching other growers how to do the same—Tomich hopes the ranch can set a good example.
“It’s part of walking the talk,” Tomich said.
In addition, Russell Ranch also hosts the Long Term Research on Agricultural Systems project, a 100-year study designed to help researchers understand how variables such as rotation and nitrogen input affect crop production.
“California agriculture is constantly changing,” Tomich continued. “Every generation, it reinvents itself.”