EXERCISE A-20. TO DEMONSTRATE THE MOVEMENT 



OF WATER IN THE SOIL. 



Equipment: Two tumblers; a saucer; a strip of 

 blotting paper, and some fine dry soil. 



Method: Fill one of the tumblers with water and 

 suspend above it the strip of blotting paper with the lower 

 end dipping into the water. Fill the second tumbler with 

 fine dry soil and sprinkle three or four spoonfuls of water 

 over the surface. Make a mound of dry soil in the center 

 of the saucer and pour water into the saucer until it stands 

 one-half inch deep. 



Describe what happened in each case. 



Discussion: The force which causes the water to 

 move uphill in the blotting paper and in the saucer of soil 

 is called capillarity and the water which moves in this 

 way is known as capillary water. The capillary movement 

 of the water is usually upward, but when a light shower 

 falls on the surface of a dry soil the movement will be 

 downward and laterally as shown in the second tumbler. 



During the growing season, water is moving by capillarity 

 from the deepen- layers of soils toward the surface. If 

 allowed to do so, much of the moisture stored in the soil 

 will pass on up through the surface layer and be evaporated 

 without having been of any service to the plants growing 

 in the soil. To prevent this loss we practice shallow, fre- 

 quent cultivation, wliich keeps a protective covering of 

 loose soil over the surface. 



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