108 CAMPBELL'S SOIL CULTURE MANUAL 



clearly show the vital importance, in this great semi-arid 

 belt, of thoroughly fining and firming that portion of the 

 soil in which the roots of the plants should grow and feed, 

 we have prepared the accompanying illustration. 







( 'it! No. 10. Water-holding Capacity of Soils. 



In the glass on the right is one pound of the largest 

 buckshot we could find; in the glass on the left is one 

 pound of the very smallest bird shot we could obtain; in 

 the center is an one-ounce druggist's graduate. With 

 this graduate we measured precisely one ounce of water 

 and turned into each glass. We then shook each glass 

 to be sure that every shot was moistened all over. This 

 covered each one with a thin film of water exactly as the 

 moisture is retained around each little particle of soil. It 

 is not possible in our illustration to get rid of the free water, 

 or that portion between the shot, except by tipping the 

 glass over and holding the shot back to allow all the water, 



