26 SOILS AND FERTILIZERS 



the capacity of the soil for storing up water and giving 

 it up as needed is a matter to be considered, par- 

 ticularly since the power of the soil for absorbing 

 and retaining water may be influenced by cultivation 

 *and manuring. Before discussing the influence of 

 cultivation upon the soil water, the forms in which it 

 is present in the soil should be studied. Water is 

 present in soils in three forms : (i) bottom water, (2) 

 capillary water, and (3) hydroscopic water. 



19. Bottom Water is water which stands in the soil 

 at a general level, and fills all the spaces between the 

 soil particles. Its distance from the surface can be 

 told in a general way by the depth of surface wells. 

 Bottom water is of service to growing crops when it is 



Fig. 11. Water films surrounding soil particles. 



at such a depth that it can be brought to the plant 

 roots by capillarity, but when near the surface so that 

 the roots are immersed, very poor conditions for crop 

 growth exist. When the bottom water can be brought 

 within reach of the roots by capillarity a crop 

 has an almost inexhaustible supply. In many soils 

 known as old lake bottoms such conditions exist. 



