WVSEA Page 22 RAIN April/May 1983 Amity’s greenhouse showing reflective surface on fold-down night insulation with exterior fish tank in foreground. Solar Greenhouse/Aquaculture System One good measure of food production efficiency is the ratio of protein to energy use. Inefficient food systems have very small ratios, consuming large amounts of fuels, sunlight, or electricity for a given quantity of protein. A major challenge for all food producers from backyard gardeners to corporate farmers involves improving protein production while reducing energy requirements. The Amity Foundation has turned this challenge into a frontier. A nonprofit research and education organization in Eugene, Amity constructed a solar greenhouse in 1978 which houses a warm water fish tank. Acting as a 2000 gallon heat storage unit as well, the tank soon became an ideal habitat for channel catfish, tilapia, African perch, bluegill, and carp. In 1979, Amity’s initial success brought it one of the first USDOE A.T. Grants in Oregon. The project had three goals: to monitor and evaluate the 350 square foot passive solar greenhouse/aquaculture system; to aerate the tank with a Savonius windmill and chart its performance; and to develop locally grown fish feeds and test them. Together the results represent valuable empirical information for improving such interactive food/energy systems in the Pacific Northwest climate. Amity monitored the greenhouse’s light, temperature, and humidity, and the aquaculture tank’s dissolved oxygen, turbidity, ammonia, nitrate, phosphate, hardness, and pH. Amity used the water quality data to set fish stocking densities and feeding levels. Fish health and weight gain singled out the species best suited to greenhouse/aquaculture systems. Similarly, fish feeds were tested by comparing the growth of fish fed easily available and inexpensive crops to growth of fish fed from a costly commercial menu. Two remarkable fish which grow in a solar heated tank are tilapia and channel catfish. They permit greater stocking densities because the catfish inhabit the bottom layer and the tilapia occupy the high zones. Plump, tasty fish (V2 to % lb.) can be harvested in seven to nine months. Robust growth of tilapia can be encouraged by feeding them duckweed. This small, easy-to-grow aquatic plant compacts well into pellets and dries quickly with solar heat. Other Amity efforts were equally fruitful. One finding particularly important for overcast locales showed that reflectors on the north interior wall of a greenhouse can increase the amount of useful winter light up to 25 percent on a clear day. Water heat storage and insulating shutters brought the inside temperature up to the low 70s when outside winter temperatures were in the mid-30s to mid- 40s. The Savonius windmill—the water tank’s "solar lung” —aerated water with surprising efficiency above a 6 mph wind speed. Perhaps the most laudable result of Amity’s project is its educational and community outreach. By May 1981, over 3,000 people had visited the greenhouse during weekly tours, and 200 more literally got their hands wet in on-site workshops. Over 4,000 copies of Amity’s book. Fish Farming in Your Solar Greenhouse ($5.00) have been sold. And through participation in the Coalition for Self-Reliance, a consortium of university, governmental, neighborhood, and nonprofit organizations. Amity has catalyzed other greenhouse and gardening projects in the Eugene area. Horticulture Solar Technology The Amity Foundation also found great interest in greenhouses and "mini-greenhouses”—coldframes and cloches. These are gaining wider use as low-cost, practical techniques for raising food a greater part of the year. Amity staff developed unique cloche designs and cold frame inventions, and received a second A.T. Small Grant to disseminate its horticultural information through a guide and through educational programs. The guide. Gardening Under Cover ($10.50) by William Head, Amity coordinator and horticulturist, will be published in June. This book thoroughly discusses ways to raise food year-round in solar greenhouses, coldframes, and cloches. It features detailed illustrations and instructions on soil horticulture, organic hydroponics, pest and disease control, and more. The Amity Foundation has reached and inspired hundreds of people. Through weekly tours, a program with the Eugene School District, and a course with Lane Community College, its experience and research enjoy broad exposure. Its educational bonanza peaked with a half-hour program on the local cable TV station, emphasizing the possibilities for year-round gardening in the Pacific Northwest. And Amity staff attracted 100 farmers, local media representatives, students, and members of the local Tilth chapter (a Northwest organic growers association) for a seminar on integrating coldframes and cloches with greenhouse methods. (Amity Foundation, P.O. Box 11048, Eugene, OR 97440) OAT
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