THE MICRO-ORGANIC POPULATION OF THE SOIL 267 

 Bacterial Numbers. NH 3 and Nitrate. 



Limit 



200 



100 



200 



100 



UNTREATED SOIL 



.''' UNTR E ATEDSpjL 



19 40 



70 



130 



19 40 



70 



130 

 Days 



Case i. Small amounts of NH 3 and nitrate initially present. A relation- 

 ship is indicated between bacterial numbers and the rate of production of NH, 

 and nitrate. 



-250 



150 



50 



Bacterial Numbers. 

 TOLUENED SOIL 



500 



300 



UNTREATED SOIL 



100 



NH 3 and Nitrate. 



Limit 



14 



14 



. - 110 



Days 



Case 2. Large amounts of ammonia and nitrate initially present. No 

 relationship like that in Case i is indicated. 



FIG. 24. Relation between bacterial numbers and amounts of nitrate and 

 ammonia formed. 



