410 THE PRINCIPLES OF SOIL MANAGEMENT 



dioxid, hydrogen sulfide, marsh gas, phosphine, hy- 

 drogen, nitrogen, etc. 



It will . be noticed that these changes, like those 

 occurring in the non-nitrogenous organic matter, 

 involve a breaking down of the more complex com- 

 pounds and the formation of simpler ones; that a very 

 large number of bacteria are concerned in the various 

 steps, while even the same substances may be decom- 

 posed and the same resulting compounds formed 

 by a number of different species of bacteria. 



Present-day knowledge of the subject does not 

 make it possible to present a list of the bacteria con- 

 cerned in each step, or to name all of the intermediate 

 products formed; but for the student of the soil the 

 principal consideration is a knowledge of the circum- 

 stances under which the nitrogen is made available to 

 plants, and the conditions which are likely to result 

 in its loss from the soil. 



279. Ammonification. Decay and putrefaction 

 may be considered as a continuation of ammonification, 

 or the latter process as the beginning of the former. 

 Ammonification, as its name implies, is that stage of 

 the process during which ammonia is formed from the 

 intermediate products. 



Like the other processes of decomposition, there 

 are many species of bacteria capable of forming am- 

 monia from nitrogenous organic substances. Differ- 

 ent forms display different abilities in converting nitro- 

 gen of the same organic material into ammonia, some 

 acting more rapidly or more thoroughly than others. 

 In tests by certain investigators where the same bac- 



