Many of us dream of growing wonderful vegetables in our backyards, and doing so organically. But one of the sticky points for people in the Western United States is being able to provide enough water for good vegetable production.
A system called aquaponics appears to cover all those bases – and has the added benefit of being able to raise edible fish as well.
Although it’s not for everyone, aquaponics has some intriguing features that make it desirable to some gardeners.
Just witness the aquaponics greenhouse constructed by Mark Vierra and his son Collin at their home in Monterey, California. The two-story greenhouse that contains two fish ponds is so ideal for growing vegetables that it was actually too thick with plants this summer, notes Mark Vierra.
“We had a forest of chard in there, much more than we could use,” he said, and a tangle of tomato and cucumber plants also grow inside, in addition to a few other plants and vegetables.
Vierra said his aquaponics system began almost three years ago as a project for he and his son to work on together. Out of necessity, they’ve constructed it themselves with a lot of trial and error, mostly using materials from stores like Home Depot.
“It’s been an amazing biology experiment,” Vierra said.
Aquaponics is a combination of aquaculture and hydroponics. To make it work, you need a fish pond or tank, and a growing bed for plants. Water from the pond is pumped into the growing beds on a daily basis; the water then trickles back into the pond.
This system is mutually beneficial for the fish and the plants. The water contains fish waste, which contains ammonia. Bacteria living in the growing bed convert the ammonia to nitrogen, which then fertilizes the plants.
The process of the water trickling through the beds helps cleanse it of waste, and the water that returns to the fish is cleaner. Because the water is recirculated, little is lost in watering the plants.
By necessity, the system is completely organic.
“You can’t use any pesticides at all” because they’d affect the fish, said Vierra. “You have to be really careful.”
He has turned to biological controls such as ladybugs and parasitic wasps to curb aphids and spider mites on his plants.
He and Collin installed low-voltage pumps, powered by solar panels, to pump water into the growing beds several times a day. More than 150 fish live in twin ponds under the greenhouse, although currently the Vierras aren’t raising edible species.
However, Vierra notes, catfish, trout and other fish can be raised this way, giving urban homesteaders even more bang for their buck when it comes to growing their own food. Vierra’s ponds contain goldfish, koi and mosquito fish.
The growing beds will seem odd at first to traditional gardeners. No soil is used at all; instead, Vierra uses clay pebbles that are specially made for this purpose, although he says gravel or small rocks can also be used.
Aquaponics appears to answer some of the concerns in a normal hydroponics system, where fertilizer must be added to feed the plants, and the water must be replaced because of the buildup of excess nutrients. Likewise, keeping fish in a pond or tank necessitates water changes to prevent waste buildup. In aquaponics, natural processes turn waste into a win-win situation.
And such systems don’t even require much space. Vierra notes that when Collin went to college, he set up his own little aquaponics garden in his dorm room, and grew bulbs and herbs over a fish tank.
Aquaponics systems are also being touted as an ideal way for people in developing countries to raise their own food, because little water is required and there’s no need to obtain fertilizer.
“You can grow food very intensively this way,” said Vierra.
Those who want to learn more about aquaponics can do so through Cabrillo College in Aptos, California. The community college’s Environmental Horticulture Center has a 3,600-square-foot greenhouse devoted to aquaponics and hydroponics, and a hydroponics class is taught in the spring semester. More information is available at www.cabrillo.edu/academics/horticulture/hydroponics_aquaponics.html.
Interview with Mark Vierra, August 2013