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Aquaponics combines two of the most productive systems in their respective fields. Recirculating aquaculture systems and hydroponics have experienced widespread expansion in the world not only for their higher yields, but also for their better use of land and water, simpler methods of pollution control, improved management of productive factors, their higher quality of products and greater food safety (Box 1). However, aquaponics can be overly complicated and expensive, and requires consistent access to some inputs.
BOX 1 Benefits and weaknesses of aquaponic food production Major benefits of aquaponic food production: Sustainable and intensive food production system. Two agricultural products (fish and vegetables) are produced from one nitrogen source (fish food). Extremely water-efficient. Does not require soil. Does not use fertilizers or chemical pesticides. Higher yields and qualitative production.Organic-like management and production.Higher level of biosecurity and lower risks from outer contaminants.Higher control on production leading to lower losses.Can be used on non-arable land such as deserts, degraded soil or salty, sandy islands.Creates little waste.Daily tasks, harvesting and planting are labour-saving and therefore can include all genders and ages.Economical production of either family food production or cash crops in many locations. Construction materials and information base are widely available. Major weaknesses of aquaponic food production: Expensive initial start-up costs compared with soil vegetable production or hydroponics. Knowledge of fish, bacteria and plant production is needed for each farmer to be successful.Fish and plant requirements do not always match perfectly.Not recommended in places where cultured fish and plants cannot meet their optimal temperature ranges.Reduced management choices compared with stand-alone aquaculture or hydroponic systems.Mistakes or accidents can cause catastrophic collapse of system.Daily management is mandatory.Energy demanding.Requires reliable access to electricity, fish seed and plant seeds.Alone, aquaponics will not provide a complete diet.
Aquaponics is a technique that has its place within the wider context of sustainable intensive agriculture, especially in family-scale applications. It offers supportive and collaborative methods of vegetable and fish production and can grow substantial amounts of food in locations and situations where soil-based agriculture is difficult or impossible. The sustainability of aquaponics considers the environmental, economic and social dynamics. Economically, these systems require substantial initial investment, but are then followed by low recurring costs and combined returns from both fish and vegetables. Environmentally, aquaponics prevents aquaculture effluent from escaping and polluting the watershed. At the same time, aquaponics enables greater water and production control. Aquaponics does not rely on chemicals for fertilizer, or control of pests or weeds which makes food safer against potential residues. Socially, aquaponics can offer quality-of-life improvements because the food is grown locally and culturally appropriate crops can be grown. At the same time, aquaponics can integrate livelihood strategies to secure food and small incomes for landless and poor households. Domestic production of food, access to markets and the acquisition of skills are invaluable tools for securing the empowerment and emancipation of women in developing countries, and aquaponics can provide the foundation for fair and sustainable socio-economic growth. Fish protein is a valuable addition to the dietary needs of many people, as protein is often lacking in small-scale gardening.
Aquaponics is most appropriate where land is expensive, water is scarce, and soil is poor. Deserts and arid areas, sandy islands and urban gardens are the locations most appropriate for aquaponics because it uses an absolute minimum of water. There is no need for soil, and aquaponics avoids the issues associated with soil compaction, salinization, pollution, disease and tiredness. Similarly, aquaponics can be used in urban and peri-urban environments where no or very little land is available, providing a means to grow dense crops on small balconies, patios, indoors or on rooftops.
However, this technique can be complicated and small-scale units will never provide all of the food for a family. Aquaponic systems are expensive; the owner must install a full aquaculture system and a hydroponic system, and this is the single most important element to consider when starting an aquaponic system. Moreover, successful management requires holistic knowledge and daily maintenance of the three separate groups of organisms involved. Water quality needs to be measured and manipulated. Technical skills are required to build and install the systems, especially in the case of plumbing and wiring. Aquaponics may be impractical and unnecessary in locations with land access, fertile soil, adequate space and available water. Strong agricultural communities may find aquaponics to be overly complicated when the same food could be grown directly in the soil. In these cases, aquaponics can become an expensive hobby rather than a dedicated food production system. Moreover, aquaponics requires consistent access to some inputs. Electricity is required for all of the aquaponic systems described in this publication, and unreliable electricity grids and/or a high cost of electricity can make aquaponics unfeasible in some locations. Fish feed needs to be purchased on a regular basis, and there needs to be access to fish seed and plant seed. These inputs can be reduced (solar panels, fish feed production, fish breeding and plant propagation), but these tasks require additional knowledge and add time to the daily management, and they may be too onerous and time consuming for a small-scale system.
That said, the basic aquaponic system works in a wide range of conditions, and units can be designed and scaled to meet the skill and interest level of many farmers. There is a wide variety of aquaponic designs, ranging from high-tech to low-tech, and from high to reasonable price levels. Aquaponics is quite adaptable can be developed with local materials and domestic knowledge, and to suit local cultural and environmental conditions. It will always require a dedicated and interested person, or group of persons, to maintain and manage the system on a daily basis. Substantial training information is available through books, articles and online communities, as well as through training courses, agricultural extension agents and expert consultation. Aquaponics is a combined system, which means that both the costs and the benefits are magnified. Success is derived from the local, sustainable and intensive production of both fish and plants and, possibly, these could be higher than the two components taken separately, so long as aquaponics is used in appropriate locations while considering its limitations.
Source: Food and Agriculture Organization of the United Nations, 2014, Christopher Somerville, Moti Cohen, Edoardo Pantanella, Austin Stankus and Alessandro Lovatelli, Small-scale aquaponic food production, http://www.fao.org/3/a-i4021e.pdf. Reproduced with permission.