BUILD YOUR OWN ECOSYSTEM

Enlarge Image Image Gallery UNDERGROND HYDROPONIC GREENHOUSE/FISH TANKALTITUDE=7,000 FT. CEMENT BLOCK AND LOG CONSTRUCTION

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UNDERGROND HYDROPONIC GREENHOUSE/FISH TANK
ALTITUDE=7,000 FT. CEMENT BLOCK AND LOG CONSTRUCTION

This is the first article in a series describing the construction and use of a complete "ecosystem "—an underground hydroponic greenhouse and aquaculture tank—powered by the wind, heated by the sun and fed on compost. Sound farfetched? Maybe so, but read on . . . you might change your mind!

The unit, built on my small homestead in northern New Mexico (altitude 7,000 feet), is still in the experimental stages, but preliminary results have far surpassed our expectations. As you can see from Fig. 5, the greenhouse—four feet below ground level and banked with earth on the north side—utilizes a 1,400-gallon solar-heated catfish tank as a heat source for winter vegetable growing. A 12-volt, 200-watt Wincharger supplies the power to circulate the water through filters and a small flat-plate solar heat collector. The liquid in the fish tank acts as a "heat battery", collecting solar energy during the daytime and radiating it back into the greenhouse at night.

The vegetables are grown hydroponically in 55-gallon drums cut in half lengthwise and filled with gravel. Under the eight hydroponic tanks are two additional drums cut in half horizontally to make four compost bins in which earthworms are raised. The worms are used to feed the catfish, and the worm castings are leached to make the organic hydroponic solution which feeds the plants.

Our ecosystem was designed to be almost completely self-sustaining. The wind generates the electricity which runs the water-circulating pump, the sun heats the water and the heated (and filtered) liquid keeps the fish happy and warms the greenhouse at night. The worms and their by-products provide food for fish and plants. The only substance that comes in from "outside" is the organic matter which feeds the worms, and that from no farther away than our animal pens and compost heap.

The idea for this project has evolved slowly over the past few years. I guess it began when I saw a copy of the Lama Foundation's Growhole poster (pg. 59 in The Last Whole Earth Catalog ). The original growhole, now fallen into disuse and ruin (see Fig. 1), was built a few years ago—at an altitude of 8,000 feet-by the Lama Commune on their land near Taos, New Mexico. It consisted of an excavation dug into a south-facing slope, shored up and framed with timber, then covered with two layers of 16-mil plastic sheeting. Apparently heavy snows in the winter of 1972 crushed the structure and it was never rebuilt.

The basic principles of the growhole, as stated on the poster, are: [1] The sun is a source of free energy and [2] The earth stores heat. All greenhouses make use of the first fact . . . it's the utilization of the second that makes the growhole unique. If the warmth of the sunlight failing on such a structure during the day could be retained overnight then, ideally, no auxiliary source of heat would be necessary. The Lama prototype was an attempt to create this condition by using the moist earth inside as a heat-collecting "storage battery".

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