Aquaponics—Integration of ATTRA Hydroponics with Aquaculture A Publication of ATTRA - National Sustainable Agriculture Information Service • 1-800-346-9140 • www.attra.ncat.org By Steve Diver Aquaponics is a bio-integrated system that links recirculating aquaculture with hydroponic vegetable, NCAT Agriculture flower, and/or herb production. Recent advances by researchers and growers alike have turned aqua- Specialist ponics into a working model of sustainable food production. This publication provides an introduction ©2006 NCAT to aquaponics with brief profiles of working units around the country. An extensive list of resources point the reader to print and Web-based educational materials for further technical assistance. Contents In aquaponics, nutrient-rich effluent from fish tanks is used to fertigate hydroponic Introduction ..................... 1 production beds. This is good for the Aquaponics: Key Elements and fish because plant roots and rhizobacteria Considerations ................ 2 remove nutrients from the water. These Aquaponic Systems ....... 3 nutrients—generated from fish manure, The North Carolina State algae, and decomposing fish feed—are con- University System .......... 4 taminants that would otherwise build up The Speraneo System ... 5 to toxic levels in the fish tanks, but instead The University of the serve as liquid fertilizer to hydroponically Virgin Islands System .... 7 Aquaponic vegetable bed in Australia. grown plants. In turn, the hydroponic beds The Freshwater Institute Photo by Joel Malcolm, Backyard Aquaponics. function as a biofilter— stripping off ammo- System ................................ 8 www.backyardaquaponics.com nia, nitrates, nitrites, and phosphorus— The Cabbage Hill Farm (with permission) System ................................ 9 so the freshly cleansed water can then be recirculated back into the fish tanks. The The New Alchemy Institute .............................. 9 Introduction nitrifying bacteria living in the gravel and in Miscellaneous association with the plant roots play a criti- Systems ............................ 11 quaponics, also known as the integra- cal role in nutrient cycling; without these Organic Aquaculture .. 11 tion of hydroponics with aquaculture, microorganisms the whole system would Evaluating an Aquaponic Ais gaining increased attention as a stop functioning. Enterprise ........................ 12 bio-integrated food production system. References ...................... 13 Greenhouse growers and farmers are taking Aquaponics serves as a model of sus- note of aquaponics for several reasons: Resources ........................ 13 tainable food production by following Appendix ......................... 19 • Hydroponic growers view fish- certain principles: Bibliography on manured irrigation water as a Aquaponics .............. 19 • The waste products of one biological source of organic fertilizer that Dissertations ............25 system serve as nutrients for a sec- enables plants to grow well. ond biological system. • Fish farmers view hydroponics as • The integration of fish and plants a biofiltration method to facilitate intensive recirculating aquaculture. ATTRA—National Sustainable results in a polyculture that Agriculture Information Service increases diversity and yields • Greenhouse growers view aquapon- is managed by the National Cen- ter for Appropriate Technology multiple products. ics as a way to introduce organic (NCAT) and is funded under a hydroponic produce into the market- grant from the United States • Water is re-used through biological Department of Agriculture’s place, since the only fertility input Rural Business-Cooperative Ser- filtration and recirculation. is fish feed and all of the nutrients vice. Visit the NCAT Web site (www.ncat.org/agri. • Local food production pro- pass through a biological process. html) for more informa- tion on our sustainable vides access to healthy foods and • Food-producing greenhouses— agriculture projects. ���� enhances the local economy. yielding two products from one production unit—are naturally Hydroponics: Hydroponics is the produc- appealing for niche marketing and tion of plants in a soilless medium whereby green labeling. all of the nutrients supplied to the crop are • Aquaponics can enable the produc- dissolved in water. Liquid hydroponic sys- tems employ the nutrient film technique tion of fresh vegetables and fish pro- (NFT), floating rafts, and noncirculating tein in arid regions and on water- water culture. Aggregate hydroponic sys- limited farms, since it is a water tems employ inert, organic, and mixed re-use system. media contained in bag, trough, trench, • Aquaponics is a working model of pipe, or bench setups. Aggregate media sustainable food production wherein used in these systems include perlite, ver- plant and animal agriculture are miculite, gravel, sand, expanded clay, peat, integrated and recycling of nutrients and sawdust. Normally, hydroponic plants and water filtration are linked. are fertigated (soluble fertilizers injected • In addition to commercial appli- into irrigation water) on a periodical cycle cation, aquaponics has become a to maintain moist roots and provide a con- popular training aid on integrated stant supply of nutrients. These hydroponic nutrients are usually derived from synthetic Related ATTRA bio-systems with vocational agri- commercial fertilizers, such as calcium Publications culture programs and high school nitrate, that are highly soluble in water. Evaluating an biology classes. Aquaculture However, hydro-organics—based on solu- Enterprise The technology associated with aquapon- ble organic fertilizers such as fish hydrosyl- ics is complex. It requires the ability to ate—is an emerging practice. Hydroponic Agricultural Business simultaneously manage the production recipes are based on chemical formula- Planning Templates and marketing of two different agricultural tions that deliver precise concentrations of and Resources products. Until the 1980s, most attempts mineral elements. The controlled deliv- at integrated hydroponics and aquacul- ery of nutrients, water, and environmen- ture had limited success. However, inno- tal modifications under greenhouse condi- vations since the 1980s have transformed tions is a major reason why hydroponics is aquaponics technology into a viable sys- so successful. tem of food production. Modern aquaponic Nutrients in Aquaculture Effluent: systems can be highly successful, but they Greenhouse growers normally control the require intensive management and they have delivery of precise quantities of mineral special considerations. elements to hydroponic plants. However, This publication provides an introduction to in aquaponics, nutrients are delivered via aquaponics, it profiles successful aquaponic aquacultural effluent. Fish effluent contains greenhouses, and it provides extensive sufficient levels of ammonia, nitrate, nitrite, resources. It does not attempt to describe phosphorus, potassium, and other second- production methods in comprehensive tech- ary and micronutrients to produce hydro- nical detail, but it does provide a summary ponic plants. Naturally, some plant species are better adapted to this system than oth- of key elements and considerations. ers. The technical literature on aquaponics provides greater detail on hydroponic nutri- Aquaponics: Key Elements ent delivery; especially see papers cited in and Considerations the Bibliography by James Rakocy, PhD. A successful aquaponics enterprise requires Plants Adapted to Aquaponics: The special training, skills, and management. selection of plant species adapted to hydro- The following items point to key elements ponic culture in aquaponic greenhouses and considerations to help prospective grow- is related to stocking density of fish tanks ers evaluate the integration of hydroponics and subsequent nutrient concentration of with aquaculture. aquacultural effluent. Lettuce, herbs, and Page 2 ATTRA Aquaponics—Integration of Hydroponics with Aquaculture specialty greens (spinach, chives, basil, and products to forms more available to plants watercress) have low to medium nutritional prior to delivery to hydroponic vegetable requirements and are well adapted to aqua- beds. Other systems deliver fish effluent ponic systems. Plants yielding fruit (toma- directly to gravel-cultured hydroponic veg- toes, bell peppers, and cucumbers) have etable beds. The gravel functions as a “flu- a higher nutritional demand and perform idized bed bioreactor,” removing dissolved better in a heavily stocked, well established solids and providing habitat for nitrifying aquaponic system. Greenhouse varieties bacteria involved in nutrient conversions. of tomatoes are better adapted to low light, The design manuals and technical docu- high humidity conditions in greenhouses mentation available in the Resources sec- than field varieties. tion can help growers decide which system is most appropriate. Fish Species: Several warm-water and cold-water fish species are adapted to recir- Component Ratio: Matching the volume culating aquaculture systems, including of fish tank water to volume of hydroponic tilapia, trout, perch, Arctic char, and bass. media is known as component ratio. Early However, most commercial aquaponic sys- aquaponics systems were based on a ratio tems in North America are based on tila- of 1:1, but 1:2 is now common and tank: ilapia is a pia. Tilapia is a warm-water species that bed ratios as high as 1:4 are employed. warm-water grows well in a recirculating tank culture. The variation in range