158 TRANSFORMATION OF MINERAL SUBSTANCES 



dioxide produced by different soils are quite unlike, as is apparent 

 from the data shown in Table 35. 



Carbon Dioxide in the Soil. — Many factors are concerned in 

 the production of carbon dioxide, and since it is practically all of 

 biological origin, the effects of various factors on the development 

 of microorganisms is reflected in the amounts of the products of 

 microbial metabolism, among which is carbon dioxide. Since 



TABLE 35 



Carbon Dioxide Produced by Different Soils (from Stoklasa) 



Carbon dioxide produced 



Soil by 1 kgm. of soil in 



24 hrs. at 20° C, mgm. 



Soil relatively free from organic substances 8. 14 



Meadow soil 10.16 



Forest soil poor in organic matter 9. 12 



Forest soil rich in organic matter 16. 26 



Infertile rye and oat soil 19 . 25 



Fertile rye and oat soil 30 . 36 



Fertile wheat soil 30 . 48 



Fertile clover soil 53 . 60 



Fertile sugar-beet soil 56 . 68 



Fertile garden mould 62 . 75 



most of the organic residues of plants become incorporated in 

 the superficial portions of the soil, and microorganisms find other 

 conditions most favorable for their development in this region, the 

 largest amounts of carbon dioxide are produced near the surface, 



TABLE 36 



Carbon Dioxide Evolved from Sandy Soil at Different Distances 

 from the Surface (from Lundegardh) 



Depth, CO2 per sq. meter per hour, 

 cm. gm. 



0-10 0.271 



10-20 0.084 



20-30 0.016 



30-40 0.009 



Total 0.380 



In the deeper layers of soil the gas is produced in smaller amounts 

 (see Table 36). Although produced most rapidly near the sur- 



