Nitrogen Free N2
Fixation
Industrial Fixation
Atmospheric
Fixation
Biological
Fixation
Azotobacter sp.
NH4 NO3 Legumic Rhizobium sp. NH3 Denitrification
H+
NO3− Pseudomonas sp.
NH4+
Dead
Assimilation
Bacteria
Fungi
Ammonification
Nitrification
NH4+ → NO2− → NO3−
Nitrosomonas sp. Nitrobacter sp.