Nitrogen Cycle
•Processes
–Nitrogen Fixation
–Transformations
•Nitrogen to Ammonia  (N2  to NH3 )
•Ammonia to Ammonium (NH3   to  NH4+)
•Ammonium to Nitrite (NH4+ to NO2- )
•Nitrite to Nitrate  (NO2-  to  NO3-)
•Ammonium to Nitrite Atmospheric nitrogen  (NO3-  to  N2) 
–Denitrification