How is nitrogen from the atmosphere converted into usable forms for plants?

Nitrogen from the atmosphere is converted into usable forms for plants through a process called nitrogen fixation.

Nitrogen fixation is a crucial part of the nitrogen cycle, a process that makes nitrogen available to living organisms. Nitrogen is the most abundant gas in the atmosphere, making up about 78% of the air we breathe. However, most plants cannot use nitrogen in its gaseous form directly from the atmosphere. They need it to be 'fixed' or converted into a form they can absorb and use, such as ammonium (NH4+) or nitrate (NO3-).

This conversion is primarily carried out by certain types of bacteria, known as nitrogen-fixing bacteria. These bacteria have a special enzyme called nitrogenase, which enables them to convert atmospheric nitrogen (N2) into ammonia (NH3). This process is called biological nitrogen fixation. These bacteria often live in a symbiotic relationship with leguminous plants, residing in nodules on the plant roots. The bacteria benefit from the plant's supply of carbohydrates, while the plant benefits from the ammonia produced by the bacteria, which it can then convert into amino acids, proteins, and other essential compounds.

In addition to biological nitrogen fixation, there are also non-biological processes that can fix nitrogen. For example, lightning can cause nitrogen and oxygen in the atmosphere to react and form nitrate, which can then be absorbed by plants. Similarly, certain industrial processes, such as the Haber-Bosch process, can artificially fix nitrogen by combining nitrogen and hydrogen under high pressure and temperature to produce ammonia.

In summary, nitrogen from the atmosphere is converted into usable forms for plants through a combination of biological and non-biological processes, all of which are essential components of the nitrogen cycle.