According to NASA, the total composition of air in the earth’s atmosphere consists of 78% nitrogen gas, 21 of oxygen, 0.93% argon, 0.04% carbon dioxide, and small amounts of other gases. Many cellular components are also made up of nitrogen. Despite all of it, the concentration of usable form of nitrogen is very less. Nitrogen gas is vital but a limiting element. All organisms including humans, plants, and certain protozoan, demand nitrogen for their daily cellular activities.
There is a huge demand for nitrogen gas. Now the question is, How does the environment meet all these demands? Let us learn about nitrogen fixation in details.
What is Nitrogen Fixation?
Nitrogen fixation is the essential biological process and the initial stage of the nitrogen cycle. In this process, nitrogen in the atmosphere is converted into ammonia (another form of nitrogen) by certain bacterial species like Rhizobium, Azotobacter, etc. and by other natural phenomena.
Plants are the main of the sources of food. The nutrients obtained from plants are synthesized by plants using various elements which they obtain from the atmosphere as well as from the soil. This group of elements includes nitrogen as well. Plants obtain nitrogen from the soil through the process of protein synthesis. Unlike carbon dioxide and oxygen, atmospheric nitrogen cannot be obtained through stomata of leaves. Because the concentration of nitrogen gas present in the atmosphere can not be directly used by plants and also the concentration of usable form of nitrogen in the atmosphere is very less. There are certain bacteria and some natural phenomenon which help in Nitrogen fixation.
Symbiotic Nitrogen Fixation
A species of bacteria called Rhizobium, help in nitrogen fixation. These bacteria live on roots of plants called legumes or leguminous plants (e.g., pea and beans plants) and using certain types of enzymes, they help in fixing nitrogen in the soil. During this biological process, they convert the non-absorbable nitrogen form into a usable form. This form of nitrogen gas gets dissolved in the soil, and plants absorb the modified nitrogen from the soil. This is the reason behind farmers implementing crop rotation, where leguminous plants help to replenish nitrogen content in the soil without the necessity of fertilizers.
Nitrogen fixation by bacteria is an example of the symbiotic relationship between Rhizobium and the leguminous plants. While bacteria fix nitrogen in the soil, plants provide them food.
Legume Root Nodules
Nitrogen Fixation by Lightning
Another process which helps in nitrogen fixation is lightning. It is a natural phenomenon where the energy of lightning breaks and converts the non-absorbable form of nitrogen into a usable form. Even though the contribution of lightning in the nitrogen fixation is small, they save plants from the deficiency of essential elements.
Natural Phenomenon -Lightning
Metabolism is a set of a chemical process, which is carried on to convert the substance into usable energy for. Nitrogen metabolism is mainly based on the recycling of ammonia (NH3) into the neutral or charged form ammonium ion (NH4+). The main part of nitrogen metabolism is the Nitrogen Cycle.
Important Questions on Nitrogen Fixation And Nitrogen Metabolism
- What is Denitrification?
Denitrification is the process of converting or reducing the nitrates back into the inert nitrogen gas. The process is carried out during the absence of oxygen by bacterial species such as Clostridium and Pseudomonas.
- What is Nitrogen Fixation?
Nitrogen Fixation is a biological process in which the nitrogen gas is converted into a usable and observable form for plants and other microbes. In this process, nitrogen gas present in the atmosphere is converted into ammonia and other related nitrogenous compounds.
- What is the importance of nitrogen?
Nitrogen is an important component of all life. It is a building block of proteins, nucleic acids and other cellular constituents which are essential for all forms of life.
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