MICROBIOLOGICAL ANALYSIS OF SOIL 



719 



cylinder through which a current of air was passing at the rate of 10 

 liters in 24 hours; for the study of anaerobic activities they substituted 

 hydrogen for air. They suggested that the determination of carbon 

 dioxide evolved by a soil under given conditions of moisture, tempera- 

 ture and time, can furnish a reliable and an accurate method for the 



n 



Fig. 59. Gas analysis apparatus: B, gas burette; H, three way stop cock; 

 A, potash apparatus (30 per cent KOH); i, index; N, mercury vessel; F, fine 

 adjustment (from Lundegardh). 



determination of bacterial activities in the soil. The presence of organic 

 matter and the temperature were found to be of greatest importance 

 in the production of carbon dioxide. Evolution of carbon dioxide was 

 found to occur most abundantly in neutral or slightly alkaline soil 

 abundantly supplied with air and readily assimilable plant nutrients; 



