PHYSICAL INTER-RELATIONS IN SOILS 35 



of loam which it would properly moisten. In other words, 

 the properly moistened loam requires just twice as much 



1906 



I80C 



/70( 

 160, 

 ISodt 

 /M 



1300 



OE 



FIG. 13. Chart indicating diagrammatically the number of English 

 heat units required to raise the amount of water, the amount of 

 dry soil, and the combinations of soil and water, respectively, shown 

 in the lower part of the chart, 33 in temperature ; that is, from 32 F. 

 to 65 F. 65 F. is the minimum desirable temperature for soils 

 for the germination of the seeds of crops. The extreme left column 

 represents 20 Ib. of water ; the next, 100 Ib. loam soil ; while the 

 others represent 100 Ib. of soil with increasing amounts of water. 

 The oblique line indicates the heat units required. 



heat to raise its temperature one degree as would the same 

 soil dry. 



