Aquaponics
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Aquaponics is the integration of aquaculture and hydroponics in a recirculating "closed water loop" cycle. The fish effluent (or fish waste) accumulated in the water as a byproduct of an aquaculture system is collected and channeled to hydroponic grow beds where the nutrient rich fish waste (toxic to fish but rich in nitrogen and other byproducts to plants) fertilizes the planted grow beds. This waste is referred to as "effluent" or "emulsion". The planted grow beds in turn digest the emulsion, reducing or elimininating the toxicity before it is returned to the fish tanks clean and recycled. Examples of aquaponic systems range from small 10 gallon aquariums to large commercial systems.
The aquaponic concept (using fish emulsion for plant fertilization) is not new to civilization, and can be traced back to early Asian and South American horticultural civilizations. However, the modern application of aquaponics can best be linked to the New Alchemy Institute in the 1970's, where researchers experimented with bioshelters and wastewater management via crop production. This pursuit of what was to become the permaculture movement inspired likeminded researchers to advance the concept of fish effluent as fertilizer for crop production. In 1986, North Carolina State University graduate student, Mark McMurtry, along with professor Doug Sanders created the first known closed loop aquaponic system (called an aqua-vegeculture system) that channeled Tilapia effluent into sand planted tomato beds. In the early 1990's, two distinct aquaponic systems emerged;1)Deep Water or Green Water Culture set up at the University of the Virgin Islands under the guidance of Dr. James Rakocy and; 2) Ebb and Flow production pioneered by Tom Speraneo of S&S Aquafarms in West Plains, Missouri.
The unique advantages of aquaponic systems are: 1) conservation through constant water reuse and recycling. 2) organic fertilization of plants with natural fish emulsion 3) the elimination of solid waste disposal from intensive aquaculture 4) the reduction of needed cropland to produce like crops 5) the overall reduction of environmental footprint for crop production.
Distinct disadvantages inherent with aquaponics are: 1) Initial expense for housing, tank, plumbing, pump/s, and grow beds 2) The infinite number of ways in which a system can be configured lends itself to equally varying results, conflicting research, and successes or failures. 3) Aquaponics relies heavily on man-made energy, technology solutions, and environmental control to achieve recirculation and water/ambient temperatures.
Aquaponic systems can be used to replicate controlled wetland conditions that are useful for reclaiming potable water from typical household sewage, in addition to generating a continual supply of food with minimal fertilizer use. Aquaponics takes advantage of synergy between self-organizing biological systems, emphasizing the one element/many functions principle of permaculture. This synergy benefits both systems and allows each to help maintain the other. For example, an aquaponic system consisting of goldfish and watercress would require less human intervention into each system. The goldfish would benefit from the filtration carried out by the watercress, and the watercress would benefit from the nutrient-rich waste excreted by the goldfish.
In practice, tilapia are the most popular fish chosen for home and commercial projects that are intended to raise edible fish. Most green leafy vegetables grow well in the hydroponic filter. Although sometimes selected minerals or nutrients such as iron are added, the main source of nutrients for the plants is the fish waste.
Hydroponics for an aquaponics system varies greatly from a traditional hydroponic system in that the traditional hydroponic system must be kept sterile or it will clog up. In aquaponics, the hydroponic grow bed depends on the bacterial action which converts the fish wastes into a useable form for the plants to absorb. Without the bacteria, both fish and plants would soon die.
