SOIL AIR 



251 



of lime has been shown by several investigators to increase 

 the carbon dioxide production. 1 



There is now no doubt that biological activities are largely 



4.5 



4.0 



5-5 

 5.0 

 ft 



gz-o 



U 



gi.5 



1.0 



"7i 



—A — ! — a? 



X [ft 



In 



JUNE 



JULY 



AUGU5T 



SEPT. 



Fig. 47. — Diagram showing the amount of carbon dioxide in air from 

 Volusia silt loam limed and unlimed and cropped to oats. 



responsible for the occurrence of the large quantity of carbon 

 dioxide in the soil air. There are two distinct processes in- 



1 Bizzell, J. A., and Lyon, T. L., The Effect of Certain Factors on 

 the Carbon Dioxide Content of Soil Air; Amer. Soc. Agron., Vol. 10, 

 No. 3, pp. 97-112; Mar. 1918. 



Potter, E. S., and Snyder, R. S., Carbon Dioxide Production in Soils 

 and Carbon and Nitrogen Changes in Soils Variously Treated; la. Agr. 

 Exp. Sta., Ees. Bui. 39; Feb. 1916. 



Plummer, J. K., Some Effects of Oxygen and Carbon Dioxide on Nitri- 

 fication and Ammonification in Soils; Cornell Agr. Exp. Sta., Bui. 384; 

 Dec. 1916. 



