1914] Lipman-Burgess : Ammoni^cation in Soils hy Pure Cultures 169 



availability. To be sure, two of these organisms have shown 

 themselves superior to all others in the sandy soil but with 

 different materials. 



In the case of the clay-adobe soil we find that with dried 

 blood B. tumescens stands at the top of the list and transforms 

 9.41 per cent of the nitrogen present into ammonia. With tank- 

 age in the same soil, Sarcina lutea is the most efficient ammonifier 

 and transforms 12.44 per cent of the nitrogen present into 

 ammonia. With cottonseed meal, B. tumescens is again superior 

 to all others and transforms 18.20 per cent of the nitrogen present 

 into ammonia; and finally with fish guano B. vulgaris again 

 assumes the ascendency and transforms 8.64 per cent of the 

 nitrogen present into ammonia. B. tumescens is very nearly as 

 efficient in this latter case as B. vulgaris. We have thus seen 

 that organisms which in all cases have shown their superiority 

 in other soils are also very efficient in the clay-adobe soil. 



It is clear, therefore, that only about half of the fifteen 

 organisms tested show greatest efficiency in some soil or with 

 some form of organic matter. Scrutinizing more closely the 

 efficiencies of each of these, we must concede to B. tumescens the 

 paramount place among them, for it has stood pre-eminent, in 

 five combinations of soil and fertilizer, out of fifteen, and has in 

 addition been close to first place in several other instances. 



Comparing our findings with those of Marchal, the following 

 critical statements must be made. First, that results of solution 

 cultures are no criterion as to results to be obtained in soils. 

 Secondly, that no two forms of organic nitrogen are attacked and 

 ammonified with the same vigor by any one organism. Thirdly, 

 that different soils will modify an organism 's power to ammonify 

 any one given form of nitrogen very markedly, so that it may be 

 efficient in one case and feeble in another. Fourthly, that the 

 ammonifying efficiency of organisms is greater in sandy soil, and 

 possibly in others, than in solutions, for we have obtained a 

 transformation of 41.98 per cent of peptone nitrogen and 36.06 

 per cent of bat guano nitrogen into ammonia by Sarcina lutea 

 and B. mycoides respectively in twelve days at temperatures 

 between 27° C and 30° C, while Marchal only obtained similar 

 transformations in thirty days at 30° C in albumin solutions. 



