Aquaponics: A sustainable land-use solution

At its heart, aquaponics is pretty simple concept. Fish poop in water, which fertilizes a crop. The plants filter and clean the water for the fish. This is a natural relationship as old as time and with today’s technology it can be had right in your backyard.

But when the urban farmer dives into the idea for the first time they might feel like they are drowning in info. Luckily, CNGF’s Deeksha Chopra wrote this life jacket article that gives the ins and outs on aquaponics.

An alternative to conventional farming that promotes a sustainable food production method

By Deeksha Chopra

Aquaponics is a controlled environment farming technique, a synthesis of aquaculture (the farming of fish and other marine life in a closed environment) and hydroponics (growing plants without soil) that mimics a natural aquatic ecosystem.

A Sustainable Living Solution

Aquaponics supports sustainable agriculture by mimicking natural systems with minimal environmental impacts and can be a step toward addressing the urban food and nutrition issues.

This system can be made at variety of scales suitable for different uses such as a hobby or for personal development, community and economic development and also as a teaching tool providing hands-on learning experience in science education emphasizing sustainable agricultural methods and healthy land-use options.

Aquaponics at California Native Garden Foundation is a moderately sized system that grows a mix of vegetables ranging from tomatoes, different types of lettuces, herbs and superfoods.

It has an automatic monitoring system that continuously monitors critical parameters such as light hours, pH, water quality, and suspended solids, to ensure successful working of the system. The system has been functioning well with high plant growth rate and plans to sell the produce at local farmer’s markets and CSAs are already in place.

CNGF’s Aquaponics not only produces high-quality plants but also educates young leaders through its nature camp classes, school field trips and community events. The system also generates revenue from plant sales and educational programs.

CNGF is expanding on this project with its school partners and proposing similar plans with developers (roof-top Aquaponics) as part of housing projects.

System Sustainability

While initial setup costs and education might seem daunting, the benefits of Aquaponics far outweigh these points.

Economically, even though these systems require substantial initial investments, they offer low recurring cost and high returns from production of both fish and vegetables.

Socially, Aquaponics promotes quality of life by providing high-quality locally grown food and fish protein — a valuable dietary supplement–available at a small scale (or home-based).

Environmentally, the system prevents effluents such as nitrates to be discharged into rivers and oceans that eventually pollute the watersheds, unlike any other traditional farm agriculture or aquaculture. The system does not employ any harmful chemicals or fertilizers for crop production, uses only 10 percent of water generally required and produces little to no waste products.

Aquaponics is supportive, quite adaptable and proves most productive in methods of growing vegetables and fish in areas where soil-based agriculture is difficult or impossible or if land is expensive and water is scarce (deserts, salty islands etc.).

The History Behind It

The practice of Aquaponics can be traced back to ancient times where fish waste was used as fertilizers for crops. Such an arrangement reduces environmental footprints as it recycles nutrients that would otherwise have been wasted. Not only is it water wise, but it also removes pollutants such as nitrates from surface runoffs, decreasing the risks of algae boom and polluted cloudy water in streams, rivers and oceans.

An Aquaculture research community introduced the catalyst for modern-day Aquaponics systems in the mid-1970s. Efforts were made to raise fish using edible plants that can also treat the waste products from the recirculating aquaculture systems.

The pioneer work done by New Alchemy Institute and other North American and European academic institutions in the late 1970s has evolved over decades to the present-day systems of aquaculture that use controlled-environment methods like greenhouses to increase production.

The Nitty Gritty on the System Science

Aquaponics is an integrated[1] multi-trophic system that combines the principles of aquaculture and hydroponics, where the fish waste rich in nutrients is circulated to water the plants growing in the grow beds. The plants in return clean the water that goes back to the fish.

Along with the fish waste (that has Ammonia), microbial activity plays a vital role in providing nutrition to the plants. Microbes that are present in spaces between the roots of the plants convert the fish waste and the solids into plant food by converting ammonia to nitrite, and then nitrates that act as fertilizers for plant growth. The water, thus cleaned is returned back to the fish tank.

 Controlling factors like water temperature, pH, micro- and macronutrients, dissolved oxygen, and sunlight/photo-period create a stable ecological system can be built to suit the local conditions in order to maximize crop yield and fish production.

Even with all these factors in check, knowledge and experience are critical in determining the right balance among different elements of an aquaponics system.

 A successful aquaponics farmer will research the types of fish and their food use rate and the composition of the fish food, for example, the quantity of pure proteins converted to Total Ammonia Nitrogen (TAN).

Other important elements include frequency of feeding, hydroponic system type and design, types and physiological stages of cultivated plants (leafy greens vs. fruity vegetables), plant sowing density and the chemical composition of the water influenced by the mineralization rate of fish waste.

Depending on the type of plants and the location requirements, on an average the system uses 1-3 percent of its total water volume per day. The key water quality parameters such a
s dissolved oxygen (DO), pH, temperature, total nitrogen, and water alkalinity, have an impact on the fish, plant and bacteria and thus, new water sources should be checked before use for these factors.

 

[1]Integrated Multi-Trophic Aquaculture (IMTA) refers to the farming of different aquaculture species together in a way that allows one species’ wastes to be recycled as feed for another.

 

 

Refererences and further reading:

Ariel E. Turcios and Jutta Papenbrock, A review “Sustainable Treatment of Aquaculture Effluents—What Can We Learn from the Past for the Future?”

David C. Love, Michael S. Uhl c , Laura Genello, Energy and water use of a small-scale raft aquaponics system in Baltimore, Maryland, United States, Aquacultural Engineering 68 (2015) 19–27

Goddek, S.; Delaide, B.; Mankasingh, U.; Ragnarsdottir, K.V.; Jijakli, H.; Thorarinsdottir, R. Challenges of Sustainable and Commercial Aquaponics. Sustainability 2015, 7, 4199-4224

Lewis, W.M., Yopp, J.H., Schramm, J.H.L., 1978. Use of hydroponics to maintain quality of recirculated water in a fish culture system. Trans. Am. Fish. Soc. 107,92–99.

Naegel, L.C.A., 1977. Combined production of fish and plants in recirculating water.Aquaculture 10, 17–24.

Rakocy, J.E., 1984. A recirculating system for tilapia culture and vegetable hydroponics. In: Smitherman, R.O., Tave, D. (Eds.), Auburn Symposium on Fisheries and Aquaculture. Auburn, AL, pp. 103–114.

Rakocy, J.E., 2012. Aquaponics – integrating fish and plant culture. In: Tidwell, J.H.(Ed.), Aquaculture Production Systems. Wiley-Blackwell, Oxford, UK, pp. 344–386.

Rakocy, J.E., Masser, M.P., Losordo, T.M., 2006. Recirculating Aquaculture Tank Production Systems: Aquaponics—Integrating Fish and Plant Culture. SRAC Publication 454.

Savidov, N., 2005. Evaluation of aquaponics technology in Alberta, Canada. Aquaponics J. 2, 1–6.

Sneed, K., Allen, K., Ellis, J., 1975. Fish farming and hydroponics. Aquac. Fish Farmer 2, 18–20.

Watten, B.J., Busch, R.L., 1984. Tropical production of tilapia (Sarotherodon aurea) and tomatoes (Lycopersicon esculentum) in a small-scale recirculating water system. Aquaculture 41, 271–283.

Small-scale aquaponic food production – Integrated fish and plant farming,Chapter-3, www.fao.org/3/a-i1092e/i1092e02a.pdf

“How Aquaponics Works.” How Stuff Works. N.p., n.d. Web. 20 Aug. 2015. http://home.howstuffworks.com/lawn-garden/professional-landscaping/alternative-methods/aquaponics1.htm

https://www.theaquaponicsource.com/rules-of-thumb/?v=7516fd43adaa

http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0102662

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