AMMONIFICATION 67 



solution, and inverted in a pneumatic trough containing 

 the same liquid. 



The flask and its contents should be kept, if possible, 

 at a constant temperature of about 35° C. Any nitrogen 

 which is liberated collects in the graduated tube, and 

 when sufficient has been obtained, it should be tested : 

 (i) with lime water ; (2) with a lighted taper. 



Ammonification. 



Previous to nitrification, complex organic bodies containing 

 nitrogen are broken down in the soil, with the formation of 

 ammonia. To make the best use of "insoluble" nitrogenous 

 manures like rape dust, shoddies, etc., it is essential, therefore, 

 that the soil be well supplied with bacteria capable of causing 

 ammonification in a short space of time. 



45. Measurement of Ammonificatmt. 



For this purpose the soil under examination should 

 be compared with a standard loam of known value and 

 fertility. Fifty grams of each soil (fresh soil should be 

 used) are mixed with an equal weight of sand, and to each 

 is added an equal weight (i to 2 grams) of finely ground 

 protein material. For this purpose, wheat gluten, or 

 Qgg or blood albumin may be used. Distilled water 

 is added in quantity just sufficient effectually to damp 

 the soils, and the containing vessels are stoppered up 

 and placed in an incubator or other warm place for 

 three days. At the end of that time more water is 

 added, the ammonia which has been formed is distilled 

 off in a current of steam, and the amount estimated by 

 direct titration, or in an aliquot part, by means of 

 Nessler reagent (see 212, p. 218). 



Retention of Substances by Soil. 



Soil is capable of absorbing from solution a number of chemical 

 substances. This action is partly chemical, due to interaction with 



