—by Meredith Sommers
Did you know that there is a year-round farm in our urban neighborhood? It uses solar energy, no soil, grows basil in orbiting cylinders and lettuce in nests, raises trout and tilapia—and is not slowed down by the harsh Minnesota weather.
All these technologies have been pulled together in a warehouse on Pierce Butler Route, close to those who buy and eat the fresh produce and fish they raise. The farming practice is called aquaponics. It is a combination of aquaculture, the raising of aquatic animals such as tilapia and shrimp, with hydroponics, which is growing plants without soil, and in this case, in water. Most nutrients that the plants need are from the waste produced by the fish; in turn, the fish benefit from the oxygen released by the plants. It is a symbiotic relationship.
Aquaponic farming is not new. It has been used for centuries. An example from the ancient city of Tenochtitlan, now known as Mexico City, are the chinampas, or stationary islands built in lakes where food was grown by the Aztec people before the conquest. Harvesting was done from canoes. Due to the warm and sunny climate, the Aztec farmers had up to nine harvests of corn, squash and beans per year. The fish in the lakes were caught and used to supplement the diet of the people.
Our neighborhood farm, called Garden Fresh Farm, is in an old warehouse. Basil is grown in orbiting cylinders with a flow-through watering system. In an area about the size of a city bus, 20 of these cylinders rotate constantly and produce about 800 basil plants a day. Lettuce grows in what looks like little nests. In a space of 10 x 120 feet, 1000 heads are grown. Additional crops include many varieties of sprouts, water cress, and other herbs. Tomatoes may be next on their menu.
Freshwater fish live in tanks of aerated, gurgling water. Eventually, the fish go to local markets, including co-ops and Whole Foods. The fish water is reused after bacteria convert the ammonia in the water to nitrites and then nitrites into nitrates utilized by the plants as nutrients.
A by-product of the waste is concentrated fish emulsion. This can be used by gardeners for foliar feeding—fertilizing through the leaves of plants. This natural fertilizer can also be worked into the garden soil to increase yields.
In addition to solar panels on the roof of the warehouse farm, artificial lighting is needed, and LEDs are used to extend the growing day.
There are other local aquaponic farms being developed in St. Paul, located in former breweries. Hamm’s Brewery on the East Side is built over artesian wells that now provide fresh water to veggies and fish. Urban Organics, the founding organization, is also repurposing the former Schmidt Brewery on West 7th Street.
This year-round growing system claims to use land 100 times more efficiently than traditional farming, with less water and energy and reduced waste. And, being located in urban neighborhoods, transportation costs are relatively small because the markets and consumers are located nearby. Buying local is becoming a year-round possibility.
[Meredith Sommers is a life-long gardener, forager, and seeker of innovation.]