THE NITROGEN CYCLE 



235 



The Nitrogen Cycle 



Nitrogen Fixing 

 Bacteria 



Plants 



Nitrates, 

 Nitrites, 

 Ammonia, 



Free Nitrogen 



Proteins, fats. 

 Carbohydrates, etc. 



i 

 Animals 



-Bacteria 



•< Urea, Proteins 



(Proteolytic Amino-acids, etc. 



Nitrifying and 

 De-nitrifying) 



