In general, nitrogen has 5 steps
(1) Nitrogen fixation (N2 to NH3/ NH4+ or NO3)
(2) Nitrification (NH3 to NO3-)
(3) Assimilation (Incorporation of NH3 and NO3- into biological tissues)
(4) Ammonification (organic nitrogen compounds to NH3)
(5) Denitrification(NO3- to N2)
Hope this helps
