48 THE SOILS ^ND CROPS OP THE FARM. 



€olor of !^oil. — The color of a soil is a matter of 

 some importance. Not only is a dark-colored soil 

 warmer than a light- colored one, but the dark color 

 is generally an indication of fertility, as it is usually 

 the result of a considerable percentage of humus in 

 the soil. 



The Sab-soil. — The character of the sub- soil has 

 much to do with the fertility of a soil. The surface 

 soil may have the best possible chemical composition 

 and the most desirable physical characteristics, but if 

 it has an undesirable sub-soil at the depth of a few 

 inches, its ability to produce crops is greatly lessened. 

 A sub-soil of impervious clay or hard-pan is very ob- 

 jectionable. A soil so underlaid cannot have a large 

 store of plant food. In wet weather crops will suffer 

 from excess of moisture; in dry weather from drouth. 

 A coarse sand or gravel sub -soil near the surface is 

 also objectionable. The water passes through too 

 readily and takes with it much plant food. 



