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Re: Kudzu's ammonia smell

     >The ratio of ammonia to nitrogen gas is mediated by the presence of
     >available carbon compounds (I've been told). If I recall it properly,
     >the carbon is necessary for denitrification so ammonia production may 
     >be favored if the pellets are encased in clay. 
     >Certainly you can expect a significant production of ammonia from
     >nitrogen fertilizer used in the substrate so use small amounts
     >preferably encased in clay or Jobe's sticks. You probably prefer that
     >your nitrate become ammonia rather than gas since that is the form 
     >which is useable by plants. 
     Just like oxygen respiration, denitrification and nitrate/nitrite 
     respiration allows for the complete oxidation of an organic molecule 
     to CO2 and H2O.  These processes only take place in the absence of 
     oxygen (oxygen is actually a strong inhibitor of the reaction).  
     Nitrate serves as an electron acceptor, just as oxygen does.
     Nitrate/nitrite respiring bacteria generate ATP from the reduction of 
     nitrate to nitrite.  Nitrite is then excreted, or converted to ammonia 
     by enzyme systems not involving the respiratory chain, i.e., it does 
     not generate ATP.  I suspect nitrite is converted to ammonia by some 
     bacteria because ammonia is easier to excrete than nitrite (nitrite 
     has a positive charge, while ammonia is uncharged).  Nitrite is 
     odorless, so it could be more prevalent in our substrates, but we 
     wouldn't notice.
     Denitrifying bacteria use nitrate, nitrite, NO and N2O as electron 
     acceptors, and thus have more reduction steps to generate ATP than 
     their nitrate/nitirite respiring cousins.
     Whether or not ammonia or nitrogen gas is produced is dependent upon 
     the kinds of bacteria present in the substrate, not the amount of 
     carbon (or whether fertilizer is encased in clay).
     Source:  Gottschalk, G.  1979.  Bacterial metabolism.  Springer- 
     Verlag, New York.