Promising alternatives in agri-technology: aquaponics. (Resources in Technology)
2002; Volume: 62; Issue: 4 Linguagem: Inglês
ISSN
0746-3537
Autores Tópico(s)Innovations in Aquaponics and Hydroponics Systems
ResumoAquaponics research activities like this one may provide technology teachers with an easy introduction to the world of agriculture. Introduction The intelligent use of natural resources is not only a responsible approach to living in a technological world; it is also economical and profitable for businesses. In practice, modern agriculture has become very dependent on chemical fertilizers, the use of ground water for irrigation, and the overuse of land for the production of crops. Among all of the environmental factors that are beyond the control of farmers, many are controlled by hydroponics. Hydroponics, agriculture without the use of soil, is typically implemented in controlled environments. The producer can control temperature, light, water, nutrient, circulation of air, and the rotation of crops through the facility. Hydroponics is becoming popular for growing a fairly wide variety of crops. However, hydroponics producers are very dependent on adding plant nutrients in order to maintain production rates. Unfortunately, a hydroponics facility may operate on a narrow profit margin when the costs of chemical nutrients are added to the facility's operating budget. The enterprise must purchase the nutrient. Employees must handle the chemical compounds. The facility may have to incur the costs of treating water that is polluted with nutrient solution. An emerging alternative to traditional agriculture is aquaculture, or fish farming. It is growing in popularity among farmers who want to expand their product base. Catfish and flounder are two of the more popular fish produced in aquaculture facilities. Commercial operations use holding ponds where the fish live and grow. Many of the benefits are obvious. A reliable source of fish is available to suppliers and consumers. Dependence on fishing operations is reduced. Costs tend to stay level and predictable. However, the effects of fish waste are often difficult to control (McMurtry, Sanders, Cure, & Hodson, 1997). There is a link between hydroponics and aquaculture. A promising alternative to the use of chemical nutrients in hydroponics operations is the complementary farming of fish. This combination of hydroponics and aquaculture is called aquaponics. The waste from the fish is often the only nutrient the plants need to grow. While most hydroponics facilities are adding the fish simply to provide nutrient, some are using aquaponics as a means of expanding their product base while completely eliminating chemical fertilizers. How Aquaponics Works In hydroponics, nutrient is added to the water, which is then circulated through plant roots. Commercial hydroponics operations will load their beds so they always have crops ready for harvest. This means that there will be plants in various stages of maturity throughout the facility. Holding tanks for the fish will be located near these various growing beds. For an aquaponics operation, the water in which the fish live is circulated through the growing beds instead of using chemically treated water (H. Webb, personal communication, September 6, 2002). One of the objectives of an aquaponics operation is to provide all of the nutrient needed for the plants while simultaneously growing as large a quantity of fish as possible. The yield for the fish is measured in pounds or kilograms of fish per gallon of effluent. One pound of fish per one gallon of water is a very good yield. Another measure of yield for fish is described by the food conversion rate. It is the yield of fish per pound of feed. A food conversion of one pound of fish per one pound of feed is a good yield. An effective feed that is both affordable and easy to obtain is known as 32% protein. The aquaponics facility must decide, through research and experimentation, how to optimize the quantities and intervals for feeding fish (H. Webb, personal communication, September 6, 2002). …
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