CHAPTER 1: What is Aquaponics?
Essentially, Aquaponics is a merge of aquaculture – fish farming, and hydroponics – growing plants in a water medium, aquaponics brings you the best of both worlds.
Let’s get into more details.
Aquaponics is a bio-integrated system which includes two main elements.
• Aquaculture sub-system, consisting of fish or other animal aquatic cultures.
• Hydroponic sub-system, consisting of hydroponically-grown plants.
These two components interact via the water medium which cycles between them – and that is where the magic of aquaponics happens.
Water containing fish waste provides plants with nutrients needed for their vigorous growth. In return, the plants take up excess nitrogen, providing purified water which goes back into the tank.
To tell the whole story, I have to point out that there is a third crucial living community within an aquaponic system – the microbial community. The beneficial nitrifying bacteria are usually contained within a suitable biofilter.
By combining and connecting these different living communities, you can create a closed, self-sustaining system which can give you diverse plant and animal produce, and a lot of enjoyment while you’re growing it.
To understand aquaponics and the motives behind its development, we should look at the history of the practice.
How Does Aquaponics Work?
The main strength of aquaponics lies in the way it overcomes the drawbacks of both aquaculture and hydroponics. How is that?
Aquaculture is by its very nature heavy on the resources. Growing a large number of fish demands a large body of water which gets saturated with waste and harmful chemicals quickly, demanding big water changes.
On the other side, pure water is quite poor in nutrients, and hydroponically grown plants – especially the crop plants – demand artificial fertilizers in order to grow.
However, one of the nutrients that is highly needed for plant growth – nitrogen – is abundantly present in aquaculture wastewater, along with many secondary elements.
Here is where the perfect synergy of aquaponics happens:
• By producing excrement, fish enrich water with many mineral compounds.
• Water is circulated through a biofilter – essentially a colony of nitrifying bacteria which turn ammonia and nitrites into plant-nurturing nitrates.
• Plants consume excess nitrates and other trace elements and utilize them for vigorous growth.
• Purified (and often oxygenated) water is returned to the fish tank, supplying fish with a healthy medium.
The cycle goes on, producing high yields of both fish and vegetables.
Aquaponic Nitrogen Cycle
As you might have already noticed, beside aquatic animals and plants, there is a third group of organisms which have a key role in aquaponics.
The group in question are the microorganisms, specifically the beneficial nitrifying bacteria which make the nitrogen cycle in the aquaponic system possible. The bacteria-driven nitrogen process (Source) – currently not working) is all the “magic” behind aquaponics’ efficiency.
Why is nitrification so vital for aquaponics? Well, utilizing nitrifying bacteria is a key aspect for successful aquaponic practice for at least two reasons:
• Ammonia and nitrite buildup in water is toxic to fish. Mechanical filtration in fish ponds might remove the decaying sediment, but it can’t filter out microscopic particles or the compounds already dissolved in water. That is the task of biofilters – which contain the needed bacteria.
• Plants need nitrogen for growth. While they are able to use both ammonia and nitrates to perform their growth processes to a certain extent, nitrates are more desirable as they are easily assimilated by their roots, and are “user-friendly” to all types of plants.
History of Aquaponics
Flooding river plains were known for their fertility since the dawn of agriculture. The biggest and most productive human settlements had developed in the floodplains of great rivers, for example, the mud-rich delta of river Nile.
Naturally, people started noticing and studying the mechanics behind the phenomenon, and in time they had learned to utilize it for controlled production.
The earliest traces of activity similar to aquaponics are found in the Aztec (Source) civilization (1000 AD). Crops were grown on the surface of the raft-like islands which floated in lake shallow in the early days of the system and later in within special canals. Nutrient-rich water, waste and mud were used to irrigate and fertilize the crops on the islands. The system was known as “Chinampas”.
A completely separate branch of aquaponics developed in Asia. The large surfaces under the region’s main crop – rice and rice puddles had made a good foundation for aquaponic development.
Although the foundation is the same, contemporary aquaponic practise differs greatly from these early systems.
Some highlights from the history of modern 20th-century aquaponics include the following:
• In 1969, John Todd, Nancy Todd and William McLarney founded the New Alchemy Institute whose main project was to create a solar-powered, self-sufficient shelter. Besides shelter itself, “The Ark” was designed to provide for the year-round needs of a family of four using holistic methods to provide fish, vegetables, and also shelter.
• In the 1970s, Dr James Rakocy and his colleagues at the University of the Virgin Islands did research on using plants as natural filtration system within the fish farm system. The team developed deep water hydroponic grow beds within a large-scale aquaponic system by 1997.
• After a successful experiment in 1978, William M. Lewis and his colleagues concluded that combination of aquaculture, biofiltration and plant fertilization yielded excellent results in tomato growing ( Source ).
• In the 1980’s, Mark McMurtry and Doug Sanders successfully designed the first known closed loop aquaponic system, in which water from fish tanks irrigated cucumbers and tomatoes in grow beds with sand medium – the sand also worked as a bio-filter; the filter water was recirculated into fish tanks.
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