edibleWESTSIDE WINTER 2012
The best advice I received from David Rosenstein when I visited him at EVO Farm, his experimental aquaponics farm tucked away in a residential backyard in Mar Vista, was to close my eyes and listen.
When you do, you forget that that the 405 is only a half a mile away, and you notice the air is saturated with the sounds and smells of a gently burbling California river. When you reopen your eyes, the irony hits you: that beautifully sensual and natural sound and clean, loamy smell is coming from an artificially-enclosed ecosystem of manmade tanks that are kept humming and burbling along by an electric pump.
At first glance it’s easy to write off aquaponics—a sustainable agricultural system that combines traditional aquaculture (fish farming) with hydroponics (plant farming in water)—as a viable urban farming method. The pipes and pumps and gallons of water seem so unnatural and resource intensive, especially for water-use sensitive Angelenos. Doing the math reveals a stunning possibility: This could be how city dwellers transform the urban food environment.
That’s exactly what Rosenstein hopes to do. The ecoscience behind aquaponics isn’t difficult to grasp. Fish—tilapia, catfish, crawfish or any number of hardy freshwater species—produce waste that can become toxic if not managed. In lakes, rivers and streams, waste is transformed and used as part of a natural equilibrium maintained between bacteria and plants. Aquaponics is a clever artificial mimicry of that equilibrium, converting fish waste into a usable fertilizer (through a process called nitrification) which is then run through a hydroponics system of plant trays. The heavy lifting is done by the plants: They use up the available fertilizer in the water, which then returns to the fish habitat free of potentially deadly waste. The system provides dual food sources using minimal space and less water than it takes to keep in-ground plants flourishing.
But are the plants as robust and nutritious as they would be from a traditional soil-based garden? With a hand full of rich, loamy backyard compost, Rosenstein says yes.“ One of the goals of aquaponics is to replicate [the compost] in an aqueous state,” said Rosenstein, filtering the new soil through his fingers while noting that this kind of organic soil is achieved through many of the same digestive processes employed in aquaponics. “Plants, whether they are growing in soil or water, need the exact same amount of nutrition. We work hard to make the liquid over [in the greenhouse] as good as this.”The other goal has broader implications. Rosenstein firmly believes, and available data backs him up, that California’s water usage practices are self-defeating, simultaneously wasting a diminishing resource while driving farms out of business and steadily raising the price of food. It’s difficult to imagine that his setup actually produces more food with 95% less water than traditional agriculture, but the proof is in this 500 square foot test garden.
Can it go mainstream? Maybe even commercial? Right now this bio-mimicry is achieved and maintained on a small scale, both here and at Venice High School where Rosenstein has built another, larger aquaponic system. He hopes to effect change in one area in particular: large-scale fish farms. Mark and Brenda Eglington at Bluebeyond Fisheries, one of the largest tilapia farms in California, are working with Rosenstein to convert one of their many acres into a commercial-sized aquaponics laboratory, allowing them to more efficiently manage the farm’s waste—filtration management is a huge expenditure in fish farming—and produce a secondary crop.
“I see it as the future of farming in California,” says Rosenstein. “[Bluebeyond] is going to start small and learn, which is really the best way, and hopefully they’ll commit to a larger operation. There are ways to scale this up and make it viable.”
Preaching the aquaponics handbook to commercial interests is still a bit of a hard sell, especially when the initial infrastructure investment clouds potential future benefits. While the aquaculture industry slowly turns its ship, Rosenstein continues to pursue the urban farmer through classes he teaches at both EVO Farm and the high school and through something called garden swapping: installing aquaponic farms in borrowed backyards. This way, Rosenstein can continue his research while paying the backyard owners in copious amounts of organically grown vegetables and fish.
“I’m currently developing a small aquaponics kit,” adds Rosenstein. “And people who take my classes can work here at the farm, and I fully refund them their class fee. I could teach this for free but that’s a waste of my time and knowledge if I teach people how to do it and they don’t do anything with it. I want people to be motivated to actually go out and apply what they’ve learned and work parallel with me.”
Rosenstein’s aquaponics evangelism didn’t bloom overnight. Before he became a sustainable urban farming guru, he was producing documentaries for public television. Hundreds of hours spent researching and telling stories revealed one common theme: food. He felt that it was with food that we could potentially solve all the world’s problems.
“When I say food can solve the world’s problems, I mean it literally. What you eat and what you don’t eat determines your health. And if you care about the economy, then access to healthier food is important. I look at aquaponics as the tool to combat climate change, to reduce our dependency on imported water and to improve community health through access to good, local food.”
This philosophy admittedly puts a pretty heavy burden on the success of aquaponics. But Rosenstein doesn’t show it. He comes back to that moment when you close your eyes and hear the stream. “If I’ve had a really intense day, I walk in here and ‘ah’,” he says, visibly relaxing. “I just go into the backyard and just sit there and listen.”
EVO Farm sells its produce in harvest cycles—still living with its full root system attached—at the Mar Vista Farmers Market. Annual expenses and licensing restrictions make legally selling the fish he farms unaffordable, but interest from markets like Whole Foods and steadily climbing fish prices have Rosenstein crunching the numbers. Aquaponics class schedules are posted to both evofarm.com and on their