UNIVERSITY OF CALIFORNIA PUBLICATIONS 



IN 



AGRICULTURAL SCIENCES 



Vol. 1, No. 7, pp. 141-172 April 25, 1914 





STUDIES ON AMMONIFICATION IN SOILS 

 BY PURE CULTURES 



BY 



C. B. LIPMAN AND P. S. BUEGESS 



The study of the physiological efficiency of soil bacteria 

 rather than their number is admittedly the dominant method in 

 soil bacteriological investigations. In view of this fact it is 

 singularly striking to note how little work has been accomplished 

 in the study of some phases of the physiological efficiency of pure 

 cultures of certain groups of soil bacteria. This is especially so, 

 since the introduction of radical changes in our soil bacterio- 

 logical methods have made it necessary to repeat some, if not all, 

 of the work which had been carried out by the old methods. 

 However this may be, it remains a fact that, since the publication 

 of MarchalV splendid work on ammonification in solution 

 cultures, but scant information has been adduced from studies 

 of soil bacteria which relate to the physiology as well as the 

 physiological efficiency of even the more common ammonifying 

 bacteria. Certainly, the work carried out along this line in 

 direct soil cultures, which recent work has shown to be so far 

 superior to solution cultures, has been very meager indeed. 



In order, therefore, to glean some useful information relative 

 to the physiological efficiency of pure cultures of a number of 

 ammonia-producing bacteria, the writers deemed it wise to select 

 a number of organisms and to compare their power to produce 

 ammonia not only from one form of organic matter, but from 

 several forms, most of which have found use in farm prac- 

 ^ tiee as fertilizers. Accordingly, the following organisms in pure 



