Mar. 24, 1919 



Ammonification of Manure in Soil 



329 



AMMONIFICATION BY THE ORGANISMS IN QUESTION IN STERILIZED 



MANURED SOIL 



SOIL INOCULATED WITH THE THREE ORGANISMS SEPARATELY 



Table XII contains the data secured when the soil inoculated with 

 pure cultures of each of the three organisms separately was subjected 

 to the ammonification test previously described (p. 317). All of the 

 organisms were found to be ammonifiers, and, so far as the individual 

 organisms are concerned, the data indicates that, per organism, B. cereus 

 is the most powerful ammonifier of the three. When the plate count of 

 B. cereus showed 17,000,000 colonies per gram of soil on the tenth day 

 after inoculation, the ammonia production was 22 mgm. per 100 gm. of 

 soil (Table XII, Experiment II). On the other hand, a plate count of a 

 flask inoculated with Ps. fluorescens showed 375,000,000 colonies per 

 gram of soil on the tenth day and an ammonia production of 20.28 mgm. 

 per 100 gm. of soil (Table XII, Experiment II); and a plate count from 

 a flask inoculated with Ps. caudatus showed 220,000,000 colonies per 

 gram of soil on the eighth day and an ammonia production of 17.84 

 mgm. per 100 gm. of soil (Table XII, Experiment II). This fact does 

 not prove, however, that B. cereus is an important ammonifier in un- 

 sterilized manured soil. The data already discussed (p. 325) indicate 

 that under natural conditions the organisms of the B. cereus group are 

 present in manured soil in very small numbers and that the vegetative 

 cells quickly disappear. 



Table XII. — Ammonia produced by B. cereus and the non-spore formers inoculated sep- 

 arately into sterile manured soil 



