Nitrogen Fixation and Nitrogen Cycle Nitrogen fixation is the process by which free atmospheric nitrogen is converted into nitrogen compounds. In nature, nitrogen is fixed during lightning or by nitrogen-fixing bacteria and blue-green algae.Leguminous plants like pea and soya bean have the nitrogen fixing bacteria Rhizobium in their root nodules. The nitrogen fixed by … [Read more...] about What is Nitrogen Fixation and Nitrogen Cycle