INFLUENCE OF WATER 



21 



Dipping a marble into a 

 glass of water as shown in 

 this illustration will con- 

 vince anyone that surplus 

 water will not cling to the 

 marble when it is removed. 

 Enough water should be 

 supplied in the soil so that 

 a film of water surrounds 

 the soil grains. 



7 he six points of contact 

 leave large air spaces which 

 retard capillary attraction 

 and permit an excessive 

 amount of air and heat to 

 evaporate what little moist- 

 ure may be in cloddy 

 ground. 



The thousand marbles 

 make six thousand points 

 of contact thus showing how 

 much easier it is for moist- 

 ure to travel upward by 

 capillarity, the increased 

 surface for holding film 

 Water and diminished air 

 spaces. 



