FORMATION OF AMMONIA BY SOIL MICROBES 131 



unable to cause further transformation of the ammonia to more 

 completely oxidized inorganic compounds, such as nitrite or 

 nitrate. Consequently ammonia may be considered as the 

 inorganic end product of nitrogen, resulting from the activity of 

 microbes upon organic substances. 



It is apparent that organic nitrogenous compounds which may 

 find their way into soils are very numerous and vary greatly in 

 composition. Consequently it is not surprising that a great 

 number of different organisms are concerned in the formation of 

 ammonia. In fact, a large percentage of all the microbes found in 

 soils may be able to produce ammonia from organic materials of 

 one kind or another. The group includes large numbers of 

 different bacteria, both aerobic and anaerobic, spore-formers and 

 non-sporulating species, filamentous fungi and actinomyces. 

 These organisms vary in their ability to attack different compounds, 

 also in the speed of ammonia formation and in the environmental 

 conditions which are favorable for their action. It is apparent 

 from Table 29 that different compounds decompose with different 

 rapidity, and microorganisms vary from one another in their ability 

 to effect the transformation. 



TABLE 29 



Formation of Ammonia (mgm.) by Microorganisms from 0.5 gm. op 

 Proteins in 40 Days 



The process of formation of ammonia from organic compounds 

 of nitrogen is of such importance that, under the name ammonifica- 



