140 



I.KSSONS IN AGRICULTURE 



Does this experiment have any bearing on farm 

 practice ? What ? 



4. Capillarity of Soils 



Fill three soil tubes respectively with fine dry sand, 

 clay, and loam. The soil is held in the tubes by a cloth 

 tied over one end of each of the tubes. Set the tubes 

 in a rack as shown in the figure, so that the cloth ends 

 reach down into the tumblers, filled to equal heights 



FIG. 45. DIAGRAM SHOWING ACTION OF WATKB IN SOIL 



with water. Observe the rise of water in the different 

 soils. Note how high it rises in each tube, and the 

 time it takes. In which soil does the water rise most 

 rapidly? In which to the greatest height? Which 

 soil draws up the greatest amount of water? This 

 power of soils to draw water up from below is called 

 capillarity, and the water is called capillary water. 

 Because of this capillarity, plants are able to get mois- 

 ture from the sub-soil in times of drought. How may 



