DECOMPOSITION OF ORGANIC MATTER IN THE SOIL. 



255 



ammonia production in soils varies with the chemical and mechanical 

 composition of the latter. In some of these experiments 100 g. 

 portions of different soils were each mixed with 5 g. of dried blood, 

 sterilized in the autoclave, cooled and inoculated with equal quantities 

 of infusion from fresh soil. The following amounts of ammonia nitro- 

 gen were produced in six days: 



With all other factors constant, chemical and mechanical differences 

 in the soil used were responsible for striking variations in ammonia 

 production, as indicated by the figures given above. 



The influence of temperature and moisture conditions is fully as 

 important as that of the chemical and mechanical composition of the soil. 

 The following data secured by Lipman may be cited in this connection 

 as showing the effect of moisture: 



One-hundred-gram quantities of air-dry soil were each mixed with 

 3 g. of dried blood and varying amounts of water added. The ammonia 

 formed was distilled off and determined at the end of eight days. 

 The amounts of ammonia nitrogen found were as follows: 



