Local Urban Aquaponic Farming Model to Reduce Food Mile, Create Jobs, Enhance Food Security
January 11, 2012 | Matt Wilhalme
On the Westside of Los Angeles, in the Mar Vista district, urban farming organization, EVO Farm, is utilizing aquaponics to create a replicable and sustainable farming model that will facilitate the creation of a network of local urban farms that grow and distribute produce that exceeds organic standards.
“Who would want a big giant farm in one place when you could have 100 farms in 100 places?” asks EVO Farm’s founder David Rosenstein.
According to Rosenstein, an urban aquaponic farm doesn’t necessarily require a lot of space. Rosenstein built what he calls a “suitcase-model,” which requires only as much space as a desktop computer. He uses it for demonstration purposes at the local farmers market. Rosenstein believes that with numerous small farms distributed across cities, food miles would be reduced, jobs would be created, and communities would be able to grow heirloom varieties and other foods that do not transport well.
“For me, if you can’t walk to your farm it’s not local,” says Rosenstein.
How It Works
Aquaponic systems combine hydroponics with aquaculture to create a more optimized and sustainable food production system by solving for problems that occur in the individual systems. With hydroponics, a grower often must rely upon commercial fertilizers in order to enrich the water, while in aquaculture the fish farmer must constantly monitor the toxicity levels of the water that results from fish effluents (waste).
In aquaponics, the fish effluent in the water provides an organic nutrient source, or natural fertilizer, for the plants being grown in the system. The plants in turn consume the natural fertilizer and in the process filter and purify the water, which is subsequently recirculated back to the fish.
Similarly, the fish in the EVO Farm’s aquaponic system are fed nutrients, which they subsequently convert into waste in the form of ammonia. With the aid of a bacteria biofilter, the ammonia in the water is converted to nitrites and eventually nitrates, essentially creating a liquid fertilizer.
The nitrate infused water then flows to EVO Farm’s two deck system of rafted plants with roots submerged in the water to pick up the nitrates and other nutrients from the water in turn acting as another filter before the water is fed back into the fish tanks where the cycle begins again.
Over the past year the EVO Farm aquaponic system, primarily designed to grow leafy green vegetables, has produced more than 40 varieties of lettuce, tomatoes and other herbs. Rosenstein conservatively estimates the system can produce more than 5,000 pounds of produce.
Compared to traditional agriculture systems, Rosenstein says that aquaponics is at least 90 percent more water efficient with the only water loss coming from evaporation and the water that the plants themselves absorb. To counteract this loss, Rosenstein has installed a rain capture system.
“If you had enough storage capacity you could run the farm all year long off the grid,” he says.
Rosenstein encountered many challenges and faced a steep learning curve as he worked to develop the EVO Farm prototype in his backyard. One bump along the road included the death of the Tilapia in the system caused by a cold snap that hit Los Angeles. He has since added fish that can handle cooler temperatures. He notes, though, that the Tilapia were composted and will make their way back into the EVO Farm system as they decompose in the form of compost tea.
From a ‘learning garden’ to the Learning Garden
The EVO Farm prototype in Mar Vista is only the tip of the iceberg. Rosenstein has been contracted to build an aquaponics-based farm setup at the Learning Garden at Venice High School in Los Angeles, which is used to instruct high school students. UCLA also uses the garden to teach some of its horticulture classes.
“Through the Mar Vista Garden Tour, I stumbled upon EVO Farm and I was amazed that it was so close,” says Tina Gruen, coordinator for the Venice High School Culinary Arts and Sustainable Agriculture Academy.
Gruen noted that EVO Farm’s ability to accommodate groups as well as Rosenstein’s facility in explaining how aquaponic systems work made her want to bring him in as a specialty teacher for Venice High School students.
“My vision is that every school will have an aquaponic system in the future and aquaponics will become as second nature to students as to who wrote the Bill of Rights,” Rosenstein says. “It’s a fundamental necessity of life – not that those things aren’t quite as important.”
“Hopefully, this will just be like the ABCs for kids,” Gruen says. “It will become a lifestyle.”
Rosenstein is preparing to select a site to build his next EVO Farm in Mar Vista that will be more than 20 times larger than his current farm and capable of producing north of 100,000 pounds of food each year – enough for an entire neighborhood in Los Angeles.
“You can actually have unique colors and tastes,” Rosenstein says. “Chefs would go nuts over that stuff – well some chefs.”
Rosenstein believes that the EVO Farm model could be sustained through CSA partnerships and sales at local farmers markets. He has also received interest from several individuals who would like him to build aquaponic systems in their backyards, as well as interest from a local developer who would like one built on the roof of a building a few years down the road.
“From a business perspective it’s way better as far as risk, but I am not here to just make money,” Rosenstein says. “I am here to be the farmer.”