1914] Lipman-Burgess : Ammonification in Soils hy Pure Cultures 167 



ability of its nitrogen, cottonseed meal easily takes second place 

 and, owing to its superiority in the sandy soil, dried blood takes 

 third place. Considering the superiority of the fish guano to 

 the dried blood in the other soils, however, it is probably fairer 

 to adjudge dried blood and fish guano of equal availability from 

 the point of view of the transformation of their nitrogen into 

 ammonia by pure cultures of ammonifying bacteria. 



General Discussion 



Several of the facts which have come to light in the investiga- 

 tions above described demand a word of comment with respect 

 to their general significance. First as regards the relative 

 efficiencies at ammonification of the different organisms tested, 

 we find that there is marked variation. Indeed it is difficult to 

 find an organism among the fifteen tested which consistently 

 stands as the best ammonifier regardless of the soil and the 

 ammonifiable material employed. There are, however, one or two 

 organisms which nearly approach such a description. In other 

 words, it appears that, viewing ammonification of organic 

 nitrogen from the standpoint of pure cultures, every organism 

 will do best with a definite combination of soil and organic 

 matter. To be sure there are some organisms of those tested, even 

 though they be in the minority, which are consistently weak 

 ammonifiers. B. icteroides and Ps. fluorescens serve to exemplify 

 such. 



That B. mycoides is by no means always the most efficient of 

 ammonifjang bacteria as has heretofore been believed is clearly 

 indicated above. On the other hand, it does possess and manifest 

 marked superiority in certain cases. Thus, for example, while 

 showing poor or mediocre ammonifying power in different soils 

 with dried blood, tankage and fish guano, it manifests great vigor 

 in the case of cottonseed meal and succeeds in making the record 

 for the percentage of nitrogen transformed in the case of bat 

 guano, in which it transforms to ammonia 36.06 per cent of the 

 nitrogen present. 



