Which of the following is a common Nitrogen fixer in paddy fields?

Rhizobium Oscillatoria Frankia Azospirillum

Azospirillum

Atmospheric nitrogen is not available to plants. There are certain nitrogen fixing bacteria which converts atmospheric nitrogen into ammonium compounds and make it available to the plants. Examples include Azotobacter, Frankia, Rhizobium, Azospirillum. Out of these, Azospirillum is widely used as nitrogen fixer organism in paddy fields. It is used as biofertilizer in rice fields. It promotes the plant growth.