Answer:
Microorganisms and certain plant roots in the soil
Step-by-step explanation:
"Plants get the nitrogen that they need from the soil, where it's already been fixed by bacteria and archaea. Bacteria and archaea in the soil and in the roots of some plants have the ability to convert molecular nitrogen from the air (N2) to ammonia (NH3)... Such organisms are called "diazotrophs". From here, various microorganisms convert ammonia to other nitrogen compounds that are easier for plants to use. In this way, plants get their nitrogen indirectly from the air via microorganisms in the soil and in certain plant roots."
I hope this helps...