Introduction
The biogeochemical cycle is an important cycle in the biological world. As the name suggests biogeochemical cycles cannot be completed without living beings hence organisms are also deeply dependent on this cycle. The nitrogen cycle is one of the most important biogeochemical cycles of all the cycles. It is an essential element and it plays a vital role in the formation of the body of an organism. Nitrogen present in the earth’s atmosphere enters the biological environment through various processes. Different plants and animals present in the biological environment use nitrogen in different fields. After nitrogen is used, it returns to the atmosphere by various processes. Thus the nitrogen cycle continues on Earth. But this cycle is not easily accomplished. The nitrogen cycle on Earth is completed by certain processes. Ammonification is one such process (1) & (3).
What is ammonification?
Ammonification is the second process of the nitrogen cycle. Nitrogen present in the atmosphere is inactive or inert. Atmospheric nitrogen is converted into various nitrogenous compounds by nitrogen fixation and stored in the soil. This nitrogen is absorbed by the plants and thus flows from plants to animals according to the rules of the food chain.
When animals or plants die, their bodies are decomposed by various bacteria. As a result, nitrogen compounds released from animal excretory substances, dead bodies of plants and animals, etc. are broken down by bacteria into ammonia, nitrite, and finally nitrate compounds. Ammonification is the process by which nitrogen compounds are converted to ammonia (2) & (6).
Definition
The special process of the nitrogen cycle in which nitrogen compounds from animal’s excretory substances (animal’s feces and urine), dead bodies of plants and animals, plant waste substances, etc. are converted into inorganic ammonia (NH₃) or ammonium ions (NH₄⁺) by various bacteria and added to the soil is called ammonification (3).
Properties of ammonification
There are some properties of the ammonification process.
- The ammonification process is a special part of the nitrogen cycle.
- This process provides the organism with the nitrogen it needs to survive.
- In the process of ammonification, bacteria or other organisms, break down chemical nitrogen from dead organic matter into ammonia.
- Various substances produced during this phase or stage of the nitrogen cycle play a significant role in ecosystems.
- In ammonification, dead plants or animals and their excretory substances contain a large amount of nitrogen, which is an essential element in all living things (2) & (4).
Bacteria that help in ammonification
The presence of bacteria in the environment contributes to the cyclic rotates of nitrogen in a variety of ways. Bacteria of soil play a vital role in ammonification. These bacteria release excess ammonia into the environment during the decomposition of dead plants and animals. The bacteria that help in ammonification are known as ammonifying bacteria. Some examples are Bacillus mycoides, Bacillus ramosus, Bacillus vulgaris, Proteus, Clostridium, Pseudomonas, and Streptomyces (6).
Ammonification process
The nitrogen present in the atmosphere circulates from the atmosphere to the biological environment and again from the biological environment to the atmosphere to form the nitrogen cycle.
Ammonia formation
- Ammonification is the process of converting nitrogen compounds to ammonia. Nitrogen present in the soil is absorbed by plants and is located in the protoplasm of plant cells through the synthesis of amino acids and proteins. At first, various bacteria in the soil break down proteins with the help of protease enzymes and convert them into amino acids (2).
Protein → amino acid (the help of protease enzymes)
- Proteins and nucleic acids present in the plant body are stored in the cells. Amino acids are formed through chemical and biogeochemical processes from proteins and nucleic acids. As a result, proteins are broken down and converted to amino acids also in animal bodies (5).
Urea formation
- The amino acids produced in an animal’s body are converted into urea by chemical reactions. Amino acid and urea present in waste and dead bodies of plants and animals are converted into ammonia and ammonium salts by various bacteria. The urease enzyme breaks down urea and converts the urea to ammonia. Thus the ammonification process is completed (1).
CO(NH₂)₂ + H₂O → 2NH₃ + CO₂ (the help of urease enzymes)
Ammonia is converted to ammonium ions in the acidification process.
NH₃ + H₂O → NH₄⁺ + OH⁻
Nitrate compounds also produce ammonia. The nitrate compounds are periodically reduced and converted to ammonia.
NO₃⁻ (Nitrate) → NO₂⁻ (Nitrite) → H₂N-NO₂ (Hyponitrous acid) → NH₂OH (Hydroxylamine) → NH₃ (Ammonia).
- The nitrogen present in the air rotates between the organism and the physical environment to form a nitrogen cycle. The nitrogen is bound in the soil by nitrogen fixation. Nitrogenous compounds in the soil are located in the plant body in the form of proteins.
- Proteins and nucleic acids present in the body of plants and animals are converted into amino acids by various reactions. These amino acids are converted into urea by some enzymes. The amino acid and urea are converted into ammonia through the process of analysis by various bacteria.
- Bacillus ramosus and Bacillus vulgaris bacteria break down proteins to produce ammonia. So the influence of various bacteria in ammonification is very important (3) & (5).
Impact of ammonification
Ammonification is part of the four phases of the nitrogen cycle. This phase is very important as in this process, nitrogenous compounds are converted into ammonia and ammonium ions and mixed with soil. The importance of ammonification in nature is immense.
1. Ammonification is very important for providing nitrogen compounds in various forms, which is very essential for all living organisms.
2. In the process of ammonification the bacteria break down animal and plant proteins into simpler substances and produce various nutrients. As a result, various nutrients are available in the ecosystem.
3. Various bacteria present in the process of ammonification play a vital role in increasing soil fertility.
4. Plants present in acidic soils use ammonification methods to collect the nitrogen they need.
5. Proteins are broken down and amino acids are produced in the ammonification process. These amino acids help in various metabolic processes in plants and animals (2) & (3).
Ammonification is the process of conversion of ammonia from nitrogen. The ammonification process is just as important as the nitrogen fixation process of the nitrogen cycle.
The various microorganisms convert nitrogen in dead plants into ammonium, which converts proteins into ammonia. The ammonification process also plays a significant role in the environment. The process of ammonification makes the nitrogen cycle essential for life.
