Nitrogen in Aquapononics

Chinmay Rajwade, Co-founder, FARMVARY

The process of Nitrification Is the base of Aquaponics. Through nitrification, it is ensured that the plants and the fish survive in a balanced ecosystem, let us now understand what exactly happens in the system when we say there is nitrification happening.

1. Ammonia (NH3):
When any animal or human beings eat a certain type of food it is digested in their stomach which means the molecules of that food are broken down to form energy. The most essential and effective
nutritional factor for energy is ‘Protein’. A molecule of protein when digested releases ammonia in some form which is then further converted to urea by certain bacteria present in a digestive system. The best way to get rid of this toxic ammonia is to excrete it and hence, the urea is excreted by human beings and other animals through urine.
Something similar happens in case of fish. When fish are provided with high protein feed it leads to a formation of ammonia or ammonium ion (NH4+) in their stomach, the best way for fish to get rid of this ammonia is to release it in the water. When the water source they are living in has a less amount of ammonia as compared to what they have in their stomach they can release it faster and better. It is easier for the fish to release ammonium ion as it has a charge, but it is essential that the water source must have a less amount of ammonia in it.

2. Nitrite (NO2-)
This is the part where Aquaponics starts. Above mentioned ammonia is toxic to the fish but fortunately, certain bacteria such as Nitrosomonas, carry out oxidation of this ammonia and release
little less toxic nitrite. However, nitrite is also very toxic to the fish if available in excess quantity. The research suggests that there are multiple types of beneficial bacteria that carry out this process
but only the bacteria belonging to Nitrosomonas group have been discovered and observed. This process of nitrification is basically biological oxidation of ammonium ion. This process is not limited to Aquaponics, this happens in soil and hence materials like ‘Cow dung’ turn out to be a good source of fertigation for plants.

3. Nitrate (NO3-):
The further oxidation of Nitrite ion leads to the formation of least toxic Nitrate in the water. Nitrate is a rich source of nitrogen available in the oil for ready absorption by the plant roots for their growth. Similarly, in Aquaponics systems nitrate plays an essential role in plant growth.Nitrification is the basic requirement for ecological development and aquaponics is a live example of how essential it is. Let us now understand the factors that can affect the process of nitrification in your Aquaponics system

The process of nitrification best happens if the pH level of water is maintained between 6.5 to 7.5 The process of nitrification leads to release of acidic hydrogen ion and hence it lowers the pH of your system.

It is recommended not to change pH of your system forcefully or rapidly, that will shock the bacteria and hence it will put a halt to nitrification.

Fish Feed:
It is essential to feed the fish regularly and sufficiently for them to generate ammonia in the system.
The fish feed must contain a good amount of protein which leads to better growth of fish and formation of more ammonia in the system, hence promoting nitrification.

Dissolved Oxygen (DO):
The system must have plenty of dissolved oxygen for the nitrification to occur without any obstacles. DO is mainly used by Fish, bacteria and plant roots to survive and hence shortage of DO will not only halt the nitrification it will increase the risk of fish mortality.

It is important that you take care of the above-mentioned factors in order to keep your nitrification going on, and as long as your nitrification goes you can say that your aquaponics system is running fine.
It has been observed by various Aquaponics researchers that in Aquaponics when the system reached full maturity, that is after 18 months of system run, the bacterial colony is at its peak. This means the nitrification is very strong and hence there will not be any toxic content in the system.
The system gets better and better as it grows older that is only because of a bacterial colony being spread out in the entire water source. The system built over the time around the globe have been found to become immune to certain shocks after a certain period of time.
This is only possible in Aquaponics, rest of the farming techniques are degraded with time but only Aquaponics systems are meant to live for more than 20 years.


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