Evolution of CO.. 



151 



green plants during their respiration, in whieh the plants obtain their 

 oxygen as a part of the soil air and return CO2 to the gas mixture, 

 most of the COo is a result of decomposition processes carried out by 

 microorganisms. 



30 



20 



- JS 10 



E 2 

 00 u 



e s 



10 



^20 



30 



40 



Aog 



vrm 



V V 



V V 



vbV 



V 



1 



Dg 



Corn Potatoes 



Table beets Sweet clover 



I I I I I I II I I I I I II I I 



^ m ^ 00 n 

 ^ vo 00 m 1^ 



•<* ro lO 00 ■ . -. -• - 



fH rt n n M- 



in ^ r^ cTi ^ tx> o 



Period of growth (days) 

 Fig. 65. Influence of plant tle\elopment upon the e\olution from the soil of 

 carbon dioxide of microbial origin: V, height of vegetati\e de\elopment; B, 

 blooming; Dg, degeneration; D, death (from Starkey). 



The total CO2 given off is a result of the decomposition of plant 

 remains by microorganisms, chemically produced CO2, and CO2 

 given off during respiration by the roots of green plants. Lunde- 

 gardh calculated the percentage of total COo due to respiration, and 

 reached the conclusion that about 30 per cent of the total COo was 

 due to the presence of the roots. He believed that here, too, micro- 

 organisms associated with the roots had much to do with the COo 

 liberation. He concluded that, when oats were grown in sterilized 



