CAPILLARY ACTION 



143 



feet or more is depleted. This is sliown by the 

 following analyses of dry-farm soil in early spring 

 and midsummer. No attempt was made to conserve 

 the moistm-e in the soil : — 



In this case water had undoubtedly passed by 

 capillary movement from the depth of eight feet 

 to a point near the surface where direct evaporation 

 could occur. As explained in the last chapter, 

 water which is held as a film around the soil particles 

 is called capillary water; and it is in the capillary 

 form that water may be stored in dry-farm soils. 

 Moreover, it is the capillary soil-moisture alone which 

 is of real value in crop production. This capillary 

 water tends to distribute itself uniformly throughout 

 the soil, in accordance with the prevailing conditions 

 and forces. If no water is removed from the soil, 

 in course of time the distribution of the soil-water 

 will be such that the thickness of the film at any point 

 in the soil mass is a direct resultant of the various 

 forces acting at that particular point. There will 

 then be no appreciable movement of the soil-mois- 

 ture. Such a condition is approximated in late 

 winter or early spring before planting begins. The 



