BIOLOGICAL SOIL PROCESSES 



601 



Air was bubbled through sterile water, then through the Dun- 

 ham solution, and then through 50 cc. of nr H2SO4, colored with 

 methyl red, by means of a water air pump. Any ammonia 

 that was drawn across in the process was caught in the acid. 

 As the acid lost color, more acid was added. 



Milligrams of ammonia formed per 100 cc. Dunham's solution 



No. I. Excess air 120.53 



No. II. Air 155.72 



No. III. Without air (oil) 163.20 



From these data it would appear that ammonification pro- 

 ceeded best without air, next with air and least with an excess 

 of air. 



Experiments were carried out with urea bouillon (no pep- 

 tone) and Dunham solution with the bacteria of the three types 

 of soil, under anaerobic, aerobic and excess aerobic conditions. 



Experiment IV. Ammonification in solution. Milligrams ammonia per 100 cc. 

 of solution. 



Urea bouillon 



It is again noticeable that urea is more readily ammonified 

 than peptone. Ammonification proceeds best under anaerobic 

 conditions. The process seems to proceed equally well with air 

 or with an excess of air. With urea bouillon the production of 

 ammonia is slightly higher with an excess of air than under 

 ordinary air conditions. With Dunham's solution the produc- 

 tion of ammonia is slightly higher without an excess of air. 



