612 



T. J. MURRAY 



Experiment XV. Denitrification in solution. Nitrogen in milligrams per 200 

 cc. of solution. 



Greenhouse 



Loam 



Clay 



NITROGEN AT KND 



20.34 

 24.33 

 20.48 



NITROGEN AT 

 BEGINNING 



56.19 

 52.19 

 51.82 



GAIN OR LOSS 



-35.85 

 -27.86 

 -30.34 



Bubbling air through the solution does not inhibit the libera- 

 tion of free nitrogen into the air by bacteria to any marked 

 extent. In every case there is less nitrogen lost when air is 

 bubbled through than under ordinary aerobic and anaerobic 

 conditions, but there is not enough difference to be of any marked 

 importance. 



From a study of these figures it is evident in each case, with 

 each type of soil, that there is least nitrogen lost under excess 

 air conditions and most lost under anaerobic conditions. 



In the following experiment denitrification was carried on in 

 solution (100 cc. of solution and 2 grams of soil) under anaerobic 

 conditions, in the anaerobic apparatus (pyrogalhc acid and 

 caustic soda) along with a nitrogen fixation experiment. 



Experiment XVI. Denitrification in solution. Nitrogen in milligrams per 100, 

 cc. solution. 



Greenhouse 



Loam 



Clay 



NITROGEN AT END 



11.76 



12.88 

 16.24 



NITROGEN AT 

 BEGINNING 



28.10 

 26.09 

 25.91 



GAIN OR LOSS 



-16.34 

 -13.11 

 - 9.67 



Most denitrification goes on in the greenhouse soil and least 

 in the clay. 



