AM.MOMFK'ATION 97 



live, and anaerobic, can form ammonia from protein. The 

 process can thus go on in the most open soils, and also in 

 those that are constantly saturated with water. The con- 

 ditions that favor the proerx an- those that favor bacterial 

 growth in general, a temperature from 20 to 40 C., 

 i s -104 F.), an abundant air supply, and a neutral re- 

 act ion. 



The rapidity with which the process proceeds is largely 

 dependent on the material undergoing decomposition. 

 Some nitrogenous fertilixers are (juiekly ammonified, as 

 dried blood, ground fish, and tankage; while cotton-seed 

 meal and leather wastes are very resistant to decomposi- 

 tion. A material resistant to decomposition can not be 

 used with success as a source of nitrogen for a quickly 

 maturing crop. 



The importance of ammonilicat ion is seen when it is re- 

 membered that every atom of nitrogen built into the tis- 

 sues of the green plant must be converted into ammonia 

 before it can again be used by the plant, either as ammonia 

 or as nitrate nitrogen. Since the process of ammonifica- 

 tion is an essential step in the cycle of nitrogen, it is neces- 

 sary that it go on at such a rate that the plant crop will not 

 be limited by the lack of nitrogen in an available form. 

 The establishment of a neutral reaction by the addition of 

 lime, the aeration of the soil by the removal of water by 

 drainage and by cultivation, are conditions that favor the 

 process of ammonification. One of the theories of dimin- 

 ished soil fertility seeks to account for reduced yields by 

 the destruction of the ammonifying bacteria by the pro- 

 tozoa in the soil. The partial sterilization of soil by heat 

 oi- by volatile antiseptics, such as carbon-disulphide, often 

 results in an increased plant growth. It has been believed 

 by some that in such treatment of the soil the protozoa were 

 destroyed, while the development of the ammonifying bac- 



