THE MICRO-ORGANIC POPULATION OF THE SOIL 267 

 Bacterial Numbers. NH, and Nitrate. 



Li mit 



200 



100 



2 00 





eo. 



so^^^ 



100 



' Untreated Soil 



-Toyy^ ' - ' 



, -""Untreated Soil 



19 40 70 



130 19 40 70 



130 

 Days 



Case I. — Small amounts of NH3 and nitrate initially present. A relation- 

 ship is indicated between bacterial numbers and the rate of production of NH3 

 and nitrate. 



NH, and Nitrate. 



500 



300- 



• 14 



100 



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. 



