Answer:
Nitrogen- fixing bacteria act as a fertilizer to produce crops.
Step-by-step explanation:
Nitrogen-fixing bacteria in the soil and within the nodules of some plants, they contain symbiotic bacteria rhizobia converts nitrogen gas into ammonia, nitrates, they all fixed nitrogen and can be absorbed by plants.
The two kinds of bacteria are recognised: symbiotic and non-symbiotic(free living). The free living bacteria include both aerobic and anaerobic bacteria like cyanobacteria, azotobacter, anabaena and nostoc, clostridium, they all are nitrogen-fixing bacteria helps to fertilize soil to prpduce crops mostly leguminous plants.