210 BACTERIOLOGICAL EXAMINATION OF SOILS 



Calcium carbonate . . . i gr. 

 Tap water ..... 200 c.c. 



Add 20 c.c. of the soil and water mixture and incubate at 20 C. 



After four or five weeks estimate the total amount of nitrogen 

 in the flask by Kjeldahl's method, and deduct from it the average 

 nitrogen content of 20 c.c. of the soil mixture which should be 

 ascertained at the beginning of the experiment. 



Ex. 102. Repeat the above experiments with : 



1. a light sandy soil, 



2. a peaty soil, 



3. an ordinary arable soil, 



4. a richly manured garden soil, 



and compare the soils in respect of their powers of nitrification, 

 denitrification, putrefaction, urea-decomposition and nitrogen- 

 assimilation. 



