Question

What is nitrogen fixation? Name various ways it is fixed in nature.

Answer 1

Nitrogen fixation is the conversion of atmospheric nitrogen into ammonia or nitrates so that plants can use it. Ways:

1. Biological fixation - symbiotic bacteria (Rhizobium, Frankia), free-living bacteria (Azotobacter, Clostridium) and cyanobacteria (Anabaena, Nostoc, Aulosira).
2. Industrial fixation - manufacture of nitrogenous fertilisers.
3. Lightning - converts N₂ and O₂ into nitrogen oxides that reach the soil as nitrates/nitrites.