FarmHub
Feasibility study: location and infrastructure considerations
Table 2 outlines the most important location and infrastructure considerations when designing a new aquaponic system. Aspect Description Site stability and foundations Water is heavy. Choose stable and level ground for building your aquaponic system. If the ground is not stable, the foundations will be unstable and leaks could occur because of movement of the pipes. Climatic conditions at the location Consider how to protect the aquaponic system from extreme weather events.
· Aqu@teachExamples of aquaponic systems around the world
A wide range of aquaponic systems exist in all continents. Table 6 summarizes several systems and their main characteristics. Europe Between the years of 2014-2018, the European Union funded COST Action FA1305 ‘EU Aquaponics Hub’, which involved the cooperation of member countries in the research of aquaponic systems as a pertinent technology for the sustainable production of fish and vegetables in the EU. The website of the action is a very good source of information, with links to fact sheets, publications, and training school videos.
· Aqu@teachEnergy requirements
As with all living animals, fish require energy, and that energy is provided by the oxidation of the organic components in feed. Fish require energy to carry out their daily activities, such as breathing and swimming, and to transform, restore, and grow their body tissues. The energy requirements of fish depend on their physiological state and on the environmental conditions. In general fish make a more efficient use of the energy ingested compared to terrestrial mammals, due to the following reasons:
· Aqu@teachElements of aquaponic systems
The ‘hardware’ of an aquaponic system consists of (i) the fish tank, (ii) the water and air pumps, (iii) the solids removal units (drum filters, settlers), (iv) the biofilter, (v) the plant grow beds, and (vi) the plumbing materials. These elements are populated by a community, where the primary producers (plants) are separated from consumers (mostly fishes), and ubiquitous microorganisms build a ‘bridge’ between the two main groups. Figure 2: Main components of an aquaponic system (redrawn after Rakocy et al.
· Aqu@teachDesigning feeds for aquaponics
Fish feeds for aquaponics can be home-made or bought from specialized feed companies that formulate specific diets depending on the species and age of the fish. Normally commercial producers use specialized feeds since they are guaranteed to meet all the nutritional needs of the fish, and tend to be more cost effective compared to making and formulating one’s own feed. However, formulated feeds are not always perfect and may have varying effects on the quality of the water where fish live and excrete waste.
· Aqu@teachCurrent research themes in aquaponics
Trends in technology As we saw above, the design of successful aquaponic systems depends on the user group. High-yield, soil-less production requires a high input of technology (pumps, aerators, loggers) and knowledge, and is therefore mostly suited for commercial operations. However, it is entirely possible to design and operate low-tech aquaponic systems that require less skill to operate, and still yield respectable results. This implied trade-off (high-tech/low-tech) and the broad range of applications of aquaponics have consequences for further development pathways for the technology, system design, and socio-economic aspects.
· Aqu@teachCrop scheduling
Planting all the crops on a farm at the same time results in production waves instead of continuous production. Continuous production is what farmers need in order to satisfy weekly or even bi-weekly demand, by always having mature crops in the farm. A planting and harvesting schedule that accounts for the life cycles of each crop is a useful tool to achieve this (Storey 2016c): Leafy greens like chard, lettuce, and cabbage have a 4-6 week cycle from transplant to harvest
· Aqu@teachConnections, water movement and aeration
Plumbing PVC pipes are most commonly used for plumbing. They are available in many standard sizes, are cost-effective, easy to cut and adapt to a wide range of adapters and connectors, and also usually last a long time. Other materials could also be used, but they must be safe for both the fish and the plants, and for food production. Some general advice about pipes: pipes have to be ‘just right’ – if the pipes are too small there will be a problem with leaks, and if they are too big the solids will not get flushed out because the water pressure will be too low
· Aqu@teachConclusions
While vertical aquaponic systems may increase the number of plants that can be grown per unit of surface area compared with horizontal systems, it is important that they also result in increased yields. From a commercial point of view, the effects of gradients within some types of vertical system on crop value will depend on how the crop is going to be processed and marketed. For example, if lettuce is grown to be sold as individual heads, then the non-uniform productivity of growing towers, living walls and static A-frame systems would be a potential weakness compared with conventional horizontal aquaponic systems or vertical stacked bed systems.
· Aqu@teachClassification of aquaponics
The delineation between aquaponics and other integrated technologies is sometimes unclear. Palm et al. (2018) proposed a new definition of aquaponics, where the majority (> 50%) of nutrients sustaining plant growth must be derived from waste originating from feeding the aquatic organisms. Aquaponics in the narrower sense (aquaponics sensu stricto) is only applied to systems with hydroponics and without the use of soil. Some of the new integrated aquaculture systems which combine fish with algae production would also fall under this concept.
· Aqu@teach