Microbiology of Soils
The nonsymbiotic bacteria which fix nitrogen live in the soil independently are

Clostridium
Azotobacter
considerably less important in comparison to the symbiotic bacteria
All of these

ANSWER DOWNLOAD EXAMIANS APP

Microbiology of Soils
Nitrogen fixation

changes the free nitrogen (N2) to a form usable by plants
especially changes nitrogen compounds, mostly amines such as NH2
fix the free nitrogen (N2) by which it should not be usable by plants
both (a) and (b)

ANSWER DOWNLOAD EXAMIANS APP