Ammonia Formation 



177 



organisms which ntih/.i> the carbohydrate as a source of energy. 

 These microbes are, tlierefore, competing -with higher plants for the 

 avaihible nitrogen compounds in the soil. As a result of these 

 studies, Doryland defined ammonification as "an expression of an 

 unbalanced ratio for microorganisms, in which the nitrogen is in 

 excess of the energy-nitrogen ratio." If the available energy ma- 



o t)U — 



o 4U — 



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 

 Incubation, days 



Fig. 75. Rate of aniinonia formation from peptone by Aspergillus niger (from 



Waksman ) . 



terial is equal to or in excess of the energy-nitrogen ratio required 

 by the flora, the coefficient of ammonia formation tends to approach 

 zero; it tends to approach a maximum if the available energy material 

 is less than the energy-nitiogen ratio. Depending on the proportion 

 of energy material to nitrogenous substances, "beneficial" bacteria 

 may become "harmful." 



The nature and the composition of the organic matter greatly influ- 

 ence its decomposition. The ratio between the carbon and nitrogen 

 of the material used is of special importance in this connection. The 

 same is true of the natnre of the non-nitrogenous organic materials 

 introduced into the soil in addition to the nitrogenous substances. 

 Table 38 has been compiled from the results of Lipman and associ- 

 ates, who added different organic nitrogenous materials to 100-gm 



