Nitrogen

Nitrogen Fixation

Recall  the  bacteria Rhizome, Colostrum and Bacteriol that can fix  nitrogen present in the air. These bacteria are present in the root nodules of legumes such as bean and pea. Sometimes nitrogen gets fixed through the action of lightning. But you know that the concentration of nitrogen remains constant in the atmosphere. You may wonder how? Let us understand in next section.

Nitrogen Cycle

Our atmosphere mainly consists of Nitrogen and Oxygen. Nitrogen constituents 78%, Oxygen 21% and other gases are present in small amounts. Nitrogen is one of the essential constituents of all living organisms as a part of proteins, chlorophyll, nucleic acid and vitamins. The atmospheric nitrogen cannot be taken directly by plants and animals. The nitrogen fixing bacteria and algae present in the soil  fix nitrogen from the atmosphere and convert into  nitrite and nitrate  forms. Once nitrogen is converted into these usable forms, it can be utilized by plants through their root system.  This is the process of 'fixing' of  nitrogen. Nitrogen is then used for the synthesis of amino acids, proteins and nitrogenous bio molecules in the plants. Animals feeding on plants get proteins and other nitrogen compounds.

The bacteria and fungi presents in the soil convert nitrogen back to nitrates and nitrites. Certain specialized bacteria convert nitrates and nitrites into nitrogen gas which goes back into the atmosphere. As a result, the percentage  of nitrogen in the atmosphere remains  more or less constant.