92 ELEMENTS OF AGfctCtJLTtmE 



table. The water table is the beginning of the free 

 water in the soil. Below the water table the soil is like 

 a great sponge filled with water, and it is from this 

 supply of free water that the soil above draws its supply 

 in dry weather. The bottom of wells must always go 

 below the water table. As film moisture evaporates 

 from the surface soil, more rises from the free water 

 below to take its place. Dip the end of a dry towel in 

 water, and notice how the water rises through the towel 

 towards the dry end; a dry sponge sucks up water in 

 the same way and illustrates perfectly how film water 

 rises towards the surface of the soil. Part of the free 

 water drains from the soil at some spring or well, and 

 the remainder rises to supply the film moisture in the 

 soil above. The supply of water in soils is renewed 

 from time to time by rain, and as more rain falls -the 

 water table rises; in very wet weather it may reach the 

 surface of the ground, and when such is the case the 

 soil is completely saturated with water. In dry weather 

 as the water drains from the soil, the water table sinks 

 lower and lower, till finally it sinks so low that almost 

 no film moisture reaches the soil above. Then a 

 drought is at hand, and plants growing in the soil 

 suffer for water. 



93. Deep and Shallow Soils. — When the impervious 

 stratum is near the surface of the soil the water table 

 is also near the surface, and consequently in rainy 

 weather the soil becomes very wet; on the other hand, 

 in dry weather the small quantity of film moisture in 

 the soil evaporates quickly, and leaves the soil very dry. 

 Such soils are said to be shallow. When the imper- 



