4 LAND DRAINAGE 



of their lives, the effect of an abundance or a shortage of 

 food in these earlier days. 



5. Chemical and physical activities. All the mineral 

 plant-food elements are found in all normal soils, and are 



FIG. 1. Drawing to show how the plant receives its several food 

 elements. Each is always combined with one or more others. 



taken by the plant from the soil through its roots. Each 

 element exists as a chemical component of some one or 

 more of the mineral 1 parts of the soil. Before they can 



1 "The few elements which exist free as constituents of rock, 

 together with many definite compounds of elements which 

 naturally take the solid form, are minerals." BLACKWELDER 

 AND BARROWS. 



