Like a number of other discoveries that people are making...that you can grow food in the city....that you can collect rainwater ... a project that I have been working on for the past year, Aquaponics, falls into that category of what's old is new again. The exciting thing for me about Aquaponics is that it is another example of a sustainability concept that can be adapted for community gardens.
Aquaponics is a combination of Aquaculture - growing fish - and Hydroponics - growing plants without soil. By combining these two things and circulating the water from the fish tanks through the plant growing medium, the fish water fertilizes the plants and the plant roots filter the fish water. The water is oxygenated as it splashes back into the fish tank and as it passes through the planting medium Nitrogen is removed which is good for plants but not so good for fish. There is more involved (the fish need to be fed!) but many companies are selling supplies and providing training. There are Aquaponics networks for teachers and for do it yourselfers.
My first project was working with a science teacher in a Junior High / High School in Queens, NY where we set up a unit that fit in an unused 3 foot by 5 foot corner of a classroom. This indoor unit complemented the school's outdoor garden. It is a perfect setting for teaching and learning science concepts and working on an ongoing science project. We hope the fish will survive the summer with less nurturing but it is set up to be a year round project growing lettuce and tilapia. The girls in the gardening club even named the fish the Pias.
Another project that in has been designed but not yet built as we wait for funding to be secured is an outdoor unit that fits in and on top of a 8 foot by 8 foot shipping container. The fish will grow in tanks inside the container with the vegetables growing in a small greenhouse on the roof. A solar panel will power a small pump to circulate the water. The project which I am working on with architect Carolin Mees is called the Urban Ag Machine. This unit is designed to fit in a small outdoor space like a corner of a community garden.
I was first introduced to concepts like this while a student at the Institute for Social Ecology at Goddard College in Vermont in 1977 hence the reference to the old being new again. At the time the New Alchemy Institute (NAI) in Woods Hole MA was creating living machines which were greenhouse structures growing food, filtering waste and powered by solar and wind power. One of the founders of NAI was John Todd who was a very influential figure in my life. Even though NAI no longer exists, Mr. Todd continues this work with Ocean Arks International and John Todd Ecological Design .
Aquaponics holds promise to help feed the world. As the units that I have been working on and the ones John Todd and others have created show, the systems can be set up almost anywhere and can be designed to satisfy local needs for fresh produce and protein. The amount of feed necessary to produce one pound of fish protein is much less than to produce one pound of meat protein. For example it takes 1.2 pounds of feed to make 1 pound of salmon while it takes 8.7 pounds of feed to produce one pound of beef.
Would an Aquaponics system work in a community garden? The system and its upkeep and maintenance would have to be well thought out. The type of fish and vegetables that are grown should work for the climate and the community gardeners. There would have to be a group of people who share the work to maintain the Aquaponics unit. The distribution of the output should be discussed and decided in advance to avoid conflicts. All of these factors should be discussed regularly and contingencies have to be made in case anything goes wrong. What happens if the fish all die or the vegetables don't thrive?
Aquaponics has risks and rewards. Many people are doing Aquaponics so there is a wealth of knowledge available to assist anyone who attempts an Aquaponics project. With all of the promise that Aquaponics offers I feel that it is something that should be promoted and supported as a local food source. What better place for Aquaponics than in a community garden.