Aquaponics is a popular technique that combines aquaculture and pisciculture, representing the new and advanced scientific turns taken by food production in recent decades.
Utilizing an aquaponic system like barramundi and tilapia, one can engage in a sustainable process that aids in crop production, fish rearing, and water conservation.
The type of fish that can be grown in an aquaponic environment is determined by both temperature and pH levels. Koi, shrimp, and trout are some examples of species that can thrive in certain systems. These fish are provided with food (ideally from a sustainable source) in order to regulate their waste and maintain control over its nutritional content.
What can be grown in Aquaponics?
The types of vegetables that can be grown in an aquaponic system depend on factors such as the types of fish, water pH, temperature, and size of the system. There are several common plants that can be grown in this type of system.
- Herbs
- Spring onions
- Spinach
- Radishes
- Lettuce
- Okras
- Cucumbers
- Cabbage
- Broccoli
- Tomatoes
Aquaponics systems comprise various types that serve both household DIY gardens and commercial purposes, including water tanks, flood and drain, and water submerged deep culture techniques.
The ammonia value of the water plays a significant role for both fish and crops in an aquaponic system, regardless of its size. Waste produced by the fish when they consume food is converted into ammonia.
If there is a lack of bacteria in the system, the ammonia will not be converted to nitrates, which are necessary for the fish to survive. Consequently, the fish will eventually die due to the toxicity of ammonia.
How does an aquaponic system work?
The main challenge when it comes to building an aquaponic system is not the difficulty, but rather the task of maintaining it, as there exist three types of living organisms in the water: fish, plants, and bacteria.
To maintain the system in order, various components are necessary.
- Rearing tank: this tank is used for rearing the fish. It can be any type of container where the fish can live.
- Biofilter: this is needed for bacterial growth so that they can convert ammonia to nitrate, which is an essential element for the growth of plants.
- Grow bed: this is the place where plants are grown and they absorb all the nutrients from the water.
- Solid remover: this is important to remove particle matter from the water.
- Water pump: the pump helps in circulating the water to and from the rearing tank.
- Fish feed: depending on the type of fish that are grown in the rearing tank, one needs to find a suitable fish feed to feed them so that their wastes are more nutritional. Some of the famous fish feeds are worms, larvae, duckweed, and many other organic feeds.
By utilizing all these components, an aquaponic system is established. Generally speaking, an aquaponic system functions as a recirculation system wherein fish thrive in fresh water and consume organic food that is essential for their daily sustenance. Similar to any other creature, fish also excrete waste that accumulates in the water.
The water turns toxic, posing a danger to the fish. To counter this, it is transferred to a growbed where microbial actions convert the ammonia to nitrate, a nutrient beneficial for plants. Consequently, the water becomes a valuable source of nutrition for various plant varieties.
Once the plants have consumed all the nitrates from the water over time, they become depleted. As a result, the water is returned to the rearing tank where the fish are fed, producing ammonia. This ammonia is then converted to nitrates by the growbed or biofilter. From this explanation, it is evident that an aquaponic system is exceptionally sustainable as it reduces the need for fertilizer and water.
Types of Aquaponics systems
There are three predominant types of aquaponics systems that can be utilized for both domestic and commercial purposes. These systems include:
- Nutrient film technique (NFT) – this technique is used both in hydroponics and aquaponics. In this system, water is enriched in nutrients and flows through small gutters as a very thin film. On top of these gutters, plants sit in small cups in such a way that their roots can touch the film and access the nutrients. This technique is mostly used for small vegetables, especially leafy ones (lettuce and strawberries) that have small roots.
- Media-filled grow beds – this aquaponic system is the simplest of all and is also suitable for growing vegetables with a bigger root. In this system, the grow bed is filled with expanded clay or river rock medium through which the fish water is pumped either in a continuous flow or in a flood and drain cycle.
- Deepwater culture (DWC or floating rafts) – this technique is a commercial process where the plants are kept floating on top of the water so that their roots can touch the water and absorb the nutrients from it. The most common type of deep water culture setup is when the fish are reared in a tank and the water is pumped out into the water channels on which floating rafts are set up with plants growing through them.
Understanding Hydroponics
Hydroponics relies on water, as implied by its name. This method involves growing plants without soil and instead using water as the medium for providing nutrients.
Instead of relying on soil, the system utilizes various inert media such as peat moss, perlite, clay pellets, and vermiculite. The main purpose of employing these inert mediums is to enable the roots to absorb nutrients from water and access oxygen effectively, facilitating their growth.
In a similar manner to aquaponics, this method excludes the presence of fish and microbes, resulting in a decreased level of complexity. People are required to supplement the plants with a nutrient solution to ensure they receive the necessary nutrients.
According to science, for a plant to produce its food, or glucose, it requires carbon dioxide and water while being exposed to sunlight and chlorophyll.
The text does not mention that soil is required for their growth. Hence, based on this idea itself, the hydroponic system was developed, allowing plants to grow using oxygen and nutrition from a nourishing solution.
What can be grown in hydroponics?
By adjusting the nutrient concentration in the growing medium, it is possible to customize it to suit the cultivation of specific plants. Hydroponics allows the growth of various items such as herbs, vegetables, and flowers.
By growing herbs, a variety of plants such as thyme, mint, parsley, oregano, fennel, cilantro, basil, and more can be cultivated. When it comes to vegetables, one can cultivate beans, cabbage, broccoli, beets, lettuce, and other varieties.
Growing vegetables such as carrots, potatoes, onions, etc., is also possible, but it demands extra attention compared to other vegetables due to their growth below the soil in their natural habitat.
When considering a hydroponic garden, it is crucial to remember that the nutrient solution holds utmost importance as it directly affects the nutritional needs of the plants, and failing to achieve the right balance of nutrients will lead to unfulfilled requirements.
Nitrogen, magnesium, potassium, sulfur, calcium, iron, zinc, boron, copper, and others are all crucial elements in a nutrient mix.
How does a hydroponic system work?
There are some conditions that are of great importance when setting up a hydroponic system in either a domestic garden or an industrial setup.
- pH: it controls the acidity and alkalinity of the nutrient mix to keep it optimum for plant growth. The basic pH level should be from 5 to 7.
- Light: proper light is a necessity for the growth of the plants. One should make sure to let the plants get some sunlight during the daytime and replace it with a full spectrum of light from fluorescent lights which can supplement the natural source of light. One can also use halide and sodium lights depending on the plants’ requirements.
- Growing medium: like it was mentioned above, in hydroponics, plants don’t require soil, but they do require certain growing mediums which will help in supplying the nutrient mix to the plants. The most common medium used is rock wool which is loose sheets of melted rock that are spun into threads.
By combining all of these components, a hydroponic system is formed, allowing plants to grow in a growth medium while a nutrient medium containing various nutritional elements flows through it.
Types of hydroponic system
There are several types of hydroponics that are very common.
- Deepwater culture– in this technique, the roots are kept suspended in the nutrient mix while an air pump oxygenates the nutrition solution. In this system, there should be no light penetrating the root and medium space to avoid algal growth.
- Nutrient film technique– this system is based on the film technique in which the nutrient solution flows continuously through the plant roots using the force of gravity. As the solution touches the root tips, there will be enough oxygenation of the roots too.
- Wicking– this is one of the simplest methods which uses a wick made of cotton whose one end is dipped into the nutrient solution and the other end is placed in the growing medium. In this way, the nutrient mix enters the growth medium and reaches the roots of the plant.
- Drip system– in this rather simple technique, the nutrient medium is slowly fed into the growing medium using a drip system. In this system, it is recommended to use the slow-draining growing medium.
- Aeroponics– in this technique, the nutrient solution is sprayed onto the roots either by using a spray nozzle or a pond fogger.
Hydro-, Aqua-, and Aeroponics
Hydroponics
One practice that involves growing plants or crops in nutrient-rich water without soil is known as hydroponics. Instead of using soil, plants are cultivated by being exposed to a continuous supply of a fertilizer solution. To support the crops, a material like rockwool, which resembles coconut fibers in appearance, is used. This material does not consume or contribute nutrients to the system but is highly absorbent. Hydroponics has several advantages, including:
- more efficient use of water because the water is filtered and recycled instead of getting leached into the soil
- increased yield versus conventional farming methods
- faster growth due to less mechanical hindrance on roots which tends to slow down growth. This means that due to the nature of having the plants above ground in hydroponic farming, the plant’s roots have an easier time growing when compared to standard farming where roots are deep in the soil.
- climate independent farming allows plants to be grown year-round at the same quality due to lab-like control of environmental conditions
- and no chemical deterrents as threats from pests are negligible.
Aquaponics
Aquaponics is the merging of hydroponics (discussed above) and aquaculture, two forms of alternative agriculture systems.
Aquaponics systems can be divided into two categories: single-loop/balanced and double-loop/de-coupled. In a balanced system, both fish and other aquatic animals are raised alongside plants. The waste generated by the animals serves as fertilizer for the plants, while the plants purify the water for the fish. This creates a closed-loop system where nutrients are recycled, resulting in water conservation of up to 98% per day.
De-coupled systems, the second category of aquaponics systems, differ from the first category in that the fish and plants are not necessarily housed within the same system. Instead, the waste produced by the fish can undergo mineralization or solidification before being utilized as fertilizer. These systems are particularly prevalent in temperate climates.
Pros and cons
Aquaponic systems may lack nutrients like Ca, K, and Fe depending on the water source and the aquatic life used. These nutrients can be supplemented in other forms. Additionally, fish are harmed by certain commonly used pesticides like copper sulfate, Rotenone, and sulfur due to their toxicity.
Aquaponics offers numerous benefits. As fish are cold-blooded, the chances of E. coli and similar diseases commonly found in agriculture are reduced. In addition, relying on fish lowers the requirement for synthetic fertilizers, resulting in reduced chemical usage and a targeted approach to pesticide application.
Aquaponics has the advantage of being able to operate in various locations, such as rooftops or unproductive sites, which helps reduce the demand for land acquisition and the strain on undeveloped land. This is particularly beneficial given the diminishing availability of farmland caused by urban expansion and soil deterioration.
Aquaponics offers several planting media choices, such as coconut, peat, and vermiculite.
Aeroponics
The process of growing plants without soil or an aggregate medium is known as aeroponics. Instead, plants are grown in an air or mist environment. In this method, the roots or lower stem of the plants are sprayed with a water solution that is rich in nutrients. Ideally, the environment in which the plants are grown is kept free from pests and diseases. However, if the environment is not completely sealed off from the outside, pests and diseases can still pose a threat.
Case studies provide valuable insights into real-life situations and can be used to examine and analyze various aspects of a particular topic or problem.
Aeroponics is found to be beneficial for growing potatoes in developing countries with low soil fertility, soil-borne diseases, poor water quality, and pests, all of which have a severe impact on potato production. In desert areas, aeroponics is particularly efficient due to its low water usage. The success of aeroponics is not dependent on soil quality and remains unaffected by seasonal adverse effects such as hot, dry, cold, or windy weather. Due to the closer spacing between each plant, aeroponics achieves the highest yield per unit area per year compared to other agricultural methods. Greenhouses utilizing aeroponics can be constructed near city centers and markets to reduce transportation needs and offer consumers fresh produce.
Despite its advantages, aeroponics also has some drawbacks. Firstly, it can be expensive to use for long-term production, mainly due to the need for advanced and well-designed equipment. Secondly, aeroponics requires growers to possess a certain level of knowledge and skill in order to operate the system effectively. Additionally, the supply of nutrients must be carefully managed to avoid oversupply, as this can lead to plant death since there is no solid medium for the plants to absorb the nutrients from. However, despite these disadvantages, the study highlights how efficient and effective aeroponics could be if implemented in developing countries.
