SOIL ORGANISMS 



419 



Table XC 



nitrate accumulation on heavily manured and on un- 

 manured soil. 





NO3 IN Paets to a Million of 

 Dry Soil 



Crop 



Unmanubed 

 Soil 



Twenty Tons 



Manure to the 



Acre for Three 



Years 



Timothy (3rd year) 



April 23rd 



June 13th 



8.2 



.8 



1.8 



17.5 



50.0 

 151.0 



ai.o 

 1.1 



August 14th 



3.0 



Maize following timothy 



May 19th 



July 6th 



August 10th 



20.1 



105.0 

 184.0 







aerated soils. Both were kept at the same temperature and 

 moisture content in the greenhouse, but no plants were grown 

 on them. The accumulation of nitrates was as follows: 



Table -KG I 



Time of Analysis 



Nitrates, Parts per Million Dry 

 Soil 





Unaeratbd Soil 



Aerated Soil 



When taken from field .... 

 After standing one month. . 

 After standing two months . 



3.2 



4.2 

 9.0 



3.2 



17.6 

 45.6 



It has often been assumed that carbon dioxide is a detri- 

 mental factor in biological activity in two respects: by the 

 replacement of oxygen and by a toxic influence on the organ- 



