52 FIELD AND LABORATORY STUDIES OF SOILS 



season, and especially in dry weather when the level of 

 standing water is many feet below the surface, plant roots 

 are supplied by capillary moisture which is moving up 

 through the soil. The depth from which water may be 



Fig. 22. — Lamp Chimneys may be Used to Show the Capillary Rise 



of Moisture. 



raised by capillary action depends upon the kind of soil. 

 Clay soils bring water from a greater depth than coarser 

 soils. Sandy soil is sometimes said to " burn out/' because 

 in a drouth it furnishes little or no water to the plant, 

 although standing water is but a few feet below the surface. 



