Bringing balance to a unique growing region
John Diener grew up on the farm next door to the one he owns now, Red Rock Ranch, in the San Joaquin Valley, near the San Andreas Fault in California. He started the 7,000-acre farm in 1980 and grows fruit and vegetables, including tomatoes, spinach, peas, grapes, corn and sugar beets, as well as almonds. Because of earthquakes in the valley over tens of millions of years, the soil in the area comes from both sides of the fault.
“On the west side of the San Joaquin Valley is old ocean bottom,” Diener says. “It has fossils and scallop shells in it. The other side is granitic in origin. They’re totally different. The center of the valley is where the two areas intermesh and overlay each other.”
Any time you have layering, you can have inhibition of water through the soil, he says, and although much of the soil is silt in the approximately 1.5 million acres of the west side of the San Joaquin Valley, a massive layer of clay from the old ocean bottom lies just feet below the surface. This causes poor drainage and expresses itself as a perched water table because it prevents irrigation water from filtering down to the deeper soil.
Another problem in the area is that the old ocean bottom soils are naturally rich in salt, and selenium, which is toxic to wildlife at high levels. When ducks eat insects that have eaten invertebrates contaminated with selenium, either the duck eggs don’t hatch or the chicks are born deformed. The soil also contains nitrates and boron, which can cause problems when they’re deposited downstream as well.
On the positive side, the ocean bottom soil consists of calcium, which makes soils soft, and magnesium, another nutrient. It’s 10 percent gypsum, which gives the soil a level of 7 pH. Gypsum is particularly useful in salty soils, because it leaches out sodium sulfate.
“The soils are so productive because they’re lightly alkaline,” Diener says. “They’re ideal to farm in.”
On the other hand, the combination of irrigation and poor drainage has raised the levels of salts and selenium, both in the soil and in drainage water—and the more efficient the irrigation, the higher the levels in the soil.
He’s looking to solve the problems both on his own farm and in the valley. “We’re trying to bring salt balance to farming,” he says. “When you look at the fields, you can’t see the problem because everything is buried below the soil, but we’ve got issues in California, and we’ve got to fix them. We have to keep moving forward. We want to solve problems—we don’t want to fight.”
Diener is one of the charter members of a subdivision of the California Department of Conservation, the Westside Resource Conservation District, which was established in 1982 to address saline drainage water management issues. He began researching drainage issues in the early 1990s and travels extensively, partnering on research and other projects with the USDA Natural Resource Conservation Service, the California Department of Water Resources (DWR), the state’s land grant colleges and other organizations at the state and national levels.
In 1999, he received the Governor’s Environmental and Economic Leadership Award, the state’s highest and most prestigious environmental honor, for his innovative Integrated On-Farm Drainage Management Farming system. In 2009, he won the Leopold Conservation Award, presented by the Sand County Foundation, the California Farm Bureau Federation and Sustainable Conservation, which recognizes landowner achievements in voluntary conservation and public education.
Management at Red Rock Ranch
Soil and water management on the farm is focused on building up the soil and moving sodium out of the system.
“Our land is relatively flat-looking, but it does have a slope and it can erode,” Diener says. “We can get hard rains here, up to two inches.”
He uses the minimum, or conservation, tillage technique, which was developed in the Midwest to keep silt—and the pollutants associated with it—from leaving the land. He keeps at least 30 percent of the residue left over after harvesting on the soil as a mulch, which achieves a number of goals. It absorbs the impact of the rain, which reduces erosion; it allows more water to infiltrate into the soil; and it improves soil structure, because the mulch becomes compost and part of the soil.
“In addition, for a carbon-based system, the less you till, the more CO2 you absorb,” he says. “It becomes part of the organic matter of the soil. Building up carbon keeps up the soil fertility.” He’s reduced the number of times he plows or discs his fields with a tractor by approximately 80 percent, which also limits fuel use and dust emissions.
He also plants native annuals that die in the summer to act as a mulch around his almond trees, and grasses as buffer strips along the edges of the fields.
“The filter strips allow water to transition through a grassy area,” Diener says, and when the grasses break down, they build up organic matter in the soil.
He irrigates his almond and grape crops with drip tape and uses low-pressure center pivot sprinklers on the row crops. The sprinklers apply large droplets to reduce evaporative losses and have smart controllers for precise irrigation scheduling.
To improve the drainage, he uses the same method that’s been used since early Roman farmers put terra cotta tiles under the soil in swampy areas to leach water away from their plants. These days, growers use flexible tubes, and place them about six feet under the soil.
His Integrated On-Farm Drainage Management System (IFDM) reuses irrigation water several times. Each time, as the density of salt and selenium increases, it’s used for increasingly salt-tolerant plants (halophytes).
“You may have to use something less valuable that tolerates some salt and nitrogen,” he says. Pasture grasses are used as winter feed for cows. Canola and mustard help remove selenium from the soil—and their oil can be extracted to produce biodiesel to fuel farm vehicles. The remaining seed meal, which is rich in selenium, can be used as a feed supplement for dairy cows or other ruminants.
After being used three or four times, though, the salt and selenium levels are so high that the water isn’t capable of sustaining plant life, so it’s sent to his solar evaporator, which harvests the salts. In addition, for the last three years, he’s been involved in a research project with UC Davis and the DWR to grow brine shrimp, which remove the selenium.
“We’ve got to be imaginative,” Diener says. “Ultimately, the answer to the Sacramento-San Joaquin Delta and the San Joaquin Valley is going to be what to do with the salt.”
Vision of the Future
Diener has partnered with the Colorado School of Mines in the design of a machine that returns 80 percent of the drainage water on his farm to potable water. The remaining brine includes chemicals that can be sold to help pay for the process. Sodium sulfate, for example, is the main ingredient in most soaps. Selenium is in vitamin pills and is good for intestinal and stomach cancers. Other chemicals in the brine include boron, nitrates, calcium and magnesium, which can be separated into caustic and sulfuric acids, sodium chloride, calcium carbonate, hydrogen and oxygen.
“All the components are already in existence,” he says. “You have to build it, run it, do the engineering. See if it’s practical on the ground. If it is, in time, larger ones will be operated by the water district.”
The machine will fit in two 40-foot containers and should arrive at his farm by late 2010. Underground pipes below the soil will convey water to cisterns on each corner of a 650-acre area on Diener’s farm. Pumps will lift the water up to the harvesting area, where 200 gallons will be processed by reverse osmosis per minute.
“This is the creative component of my life,” Diener says. “It will cost a fair amount of money, but it is a long-term deal. If you can get a return, you can pay for the environmental benefits of keeping the soil healthy.”
The author is a freelance writer based in Altadena, Calif.