Aquaponic System

Citizen garden

Introduction

The word “aquaponics” is made up of the terms “aquaculture” (a type of fish farming) and hydroponic plant cultivation (without soil). These two stand-alone systems have their advantages but also their disadvantages. Aquaponics is a combination of both techniques in a recirculation system in which the advantages outweigh the disadvantages.

The eponymous approach, which gives water a central role, is the translation of “pónos” from the Greek, which means “work”. “Aqua” from the Latin for water, loosely translated: “water work”. This reflects an essential aspect: Water as a central medium in which plants and fish thrive together in a resource-saving manner.

Aquaponics can be defined as the combination of aquaculture and hydroponic cultivation. The latter is a practice in which plants are grown without soil, using only water enriched with all the nutrients the plants need. In the case of aquaponics, the nutrients essential for plant growth are provided by fish farming of which these substances are the main waste products. In this system, elements such as nitrogen and phosphorous, derived both from the excretion and droppings of fish and from the decomposition of uneaten feed, can be absorbed by the roots of the growing plants that are directly immersed in the water.

Activity Topic

Sustainable consumption

Organisation

University Pablo Olavide

Legal Status

Public body

Activity Description

Aims and Outcomes

An aquaponics system is a recirculation system, where water is taken from the tank in which the fish are kept by one or more pumps and passed through a biofilter. The latter starts the nitrification process that will lead to the formation of nitrites and nitrates that are then assimilated by the plants. It will also decrease the amount of suspended solids as much as possible, which is very important in order to maintain good water quality and prevent the oxygen dissolved in it from decreasing. The water is then fed into the culture beds in which the cultivated plants (whose roots are in direct contact with the water) are placed and finally reintroduced into the breeding tank.

The plant varieties that can be cultivated are many, not only leafy vegetables but also plants such as courgettes, aubergines, tomatoes or herbs. Similarly, almost all freshwater fish species can be reared in aquaponics, including ornamental species and even crustaceans.

Bringing this practice into urban gardens, which is unthinkable today but desirable within a decade, would be a not inconsiderable upgrade, making it possible to add fish and crustaceans to the production of vegetables in an urban garden. Another upgrade could concern the use of refined wastewater in the aquaponic circuit instead of drinking water, so as to reduce the impact on higher quality water resources, which the current Regulation (EU) 2020/741 would allow.

Advantages and Benefits

Aquaponics can be understood as a sustainable agricultural production activity in which the cycles of key macro-nutrients are closed through the integration of two production systems, aquaculture and hydroponics. Compared to conventional farming techniques, aquaponics has several strengths, including:

Water savings: aquaponics uses around 90% less water than conventional agriculture
Limited space: As the plants do not require soil, aquaponics allows intensive cultivation in relatively limited space
No use of pesticides and pesticides: aquaponics does not involve their use. In order to avoid toxicity problems for fish and plants, biological pest control is used in aquaponics. In addition, an attempt is made to isolate the production system as best as possible from the surrounding environment so as to limit the entry of pests and pathogens
No use of fertilisers: plant nutrients are provided by fish farming
Emission control: there is no need for the use of agricultural equipment resulting in less consumption of fossil fuels.

Required Competences and Skills

Agronomic knowledge combined with knowledge of fish farming

Evaluation

Recent scientific studies demonstrate the hygiene and food safety of fish and vegetables, which could therefore be safely marketed and eaten. However, in the absence of adequate supporting EU legislation, in most European countries neither fish nor vegetables produced under this system can be used for human or animal consumption.

Conclusions

Aquaponics is not a new cultivation technique; in fact, it is since the 1970s that there has been substantial talk of it. However, it is only in recent years that it has come back into the limelight, thanks also to new scientific research and the increased focus on sustainability on the part of consumers and producers. In the United States of America, for example, aquaponics has become part of organic production techniques. On the contrary, in Europe there is a regulatory vacuum regarding aquaponics, and therefore, at the moment, although sharing all the principles of organic production, an aquaponic product cannot bear the ‘organic’ label. However, this regulatory vacuum will probably soon be filled, given the enormous interest that the European Union has shown in this farming technique, which is also evidenced by the funding and promotion of numerous projects in this regard.

Advice / Recommendation

In recent years, large production facilities have been built in countries such as the United States, Australia and New Zealand, and aquaponic practices are attracting the interest of universities and companies worldwide. At the European level, the first truly productive aquaponics realities have sprung up in recent years in the Netherlands (e.g. UF002), England (e.g. Bioaqua Farm, Growup Urban Farm) and Iceland (e.g. Akur Farm). On the other hand, in other European countries, only a few small experimental plants have been set up so far (e.g. in Seville in Spain and Bari in Italy), although it is reasonable to think that in the near future, major investments will be made in this field.

Due to the space-saving design of aquaponic systems and their efficiency, this cultivation technique will become increasingly interesting for urban areas and their surroundings. We can work with nature and not against it.

Aquaponics can be found not only in Seville, but also in the capital of Austria, Vienna, in the 22nd district, Schafflerhofstraße 156, at the company BLÜN. This urban farming start-up supplies Viennese people with local fish and vegetables and supplies renowned restaurants and selected retail partners. Currently, around 12 tons of the resource-saving “Viennese fish” are already sold every year.
The company has three basic principles: local, transparent and eco-effective. BLÜN produces in the city for the city. Product manufacturing is transparent and people are shown how it is done. There are several guided tours of the production facilities each week. Work is also eco-effective. Technical and biological cycles overlap and complement each other. Catfish are bred and a variety of vegetables such as tomatoes, eggplants, cucumbers, peppers and chili peppers are grown.

Project Number: 2023-1-FR01-KA220-ADU-000153638

The objective of the Gardeniser Academy project is to support the development of community gardens in Europe by offering online training contents tailored to the needs and expectations of gardeners all over Europe.

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Funded by the European Union. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Education and Culture Executive Agency (EACEA). Neither the European Union nor EACEA can be held responsible for them.

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