COLOR OF SOIL AND TEMPERATURE 

 Table LXXI 



457 



These figures agree with those of Schubler, who 

 found that, at one-eighth of an inch below the surface, 

 blackened soil attained a temperature from 12 to 15 

 Fahr. warmer than the same soil whose, surface was 

 made white by magnesia. 



Humus, because of the black or dark color it im- 

 parts to the soil, has a large effect on the soil tempera- 



100 



96 



t 



UJ 



I 92 



z 



UJ 



E 



1 88 

 



2 84 

 u 



cc 

 o 

 g 80 



z 



Z 76 

 cc 



z> 



72 



< 



ui 



I 68 



Ui 



I- 

 64 



60 



10 



20 



30 40 



MINUTES FROM START 



60 



60 



70 



Fig. 124. Curves showing the temperature of a dry sandy loam soil, 

 covered by a very thin layer of powdered chalk and carbon black respectively, 

 after exposure in bright sunshine. 



