While shopping at my local green grocer last night, I noticed that many of the organic lettuce greens and herbs come from a place called AquaRanch. When I asked about it, the cashier explained that the veggies were produced using "aquaponics," a technique that combines tilapia and hydroponic vegetable production in a greenhouse.

I first heard about fish emulsion fertilization via Growing Power, Will Allen's urban farming operation in Milwaukee. There, Allen has created an aquaponic system whereby tilapia and perch are farmed on-site, and the fish water is filtered and circulated to vegetable growing beds.

AquaRanch, which is located about two hours south of Chicago in Flanagan, Illinois, uses tilapia, which they sell locally. From the AquaRanch website, here's an explanation of how the aquaculture process works:

"After the primary filtration, the water flows to the grow beds where the herbs and the vegetables are grown. The roots of the plants hang down in the water and serve two purposes. First the roots directly take up nitrogen and other nutrients produced by the fish. Second, the roots act as a substrate for beneficial bacteria to break down harmful ammonia and nitrites to a less toxic form of nitrogen called nitrates."

According to a recent BuildingGreen article, AquaRanch owner Myles Harston started working with aquaponics since 1992, and he grows kale, lettuce, chard, tomatoes, herbs and hot peppers in a 12,500 square-foot greenhouse with 12 1,200-gallon fish tanks full of tilapia.

-Mark

[Growing Power photo courtesy of Flickr user gifray]