144 DRY-FARMING 
distribution of water under such conditions is seen 
in the table on page 114 of the last chapter. During 
the greater part of the year, however, no such quies- 
cent state can occur, for there are numerous dis- 
turbing elements that normally are active, among 
which the three most effective are (1) the addition 
of water to the soil by rains; (2) the evaporation of 
water from the topsoil, due to the more active meteor- 
ological factors during spring, summer, and fall; and 
(8) the abstraction of water from the soil by plant 
roots. 
Water, entering the soil, moves downward under 
the influence of gravity as gravitational water, until 
under the attractive influence of the soil it has been 
converted into capillary water and adheres to the 
soil particles as a film. If the soil were dry, and the 
film therefore thin, the rain water would move down- 
ward only a short distance as gravitational water; 
if the soil were wet, and the film therefore thick, 
the water would move down to a greater distance 
before being exhausted. If, as is often the case in 
humid districts, the soil is saturated, that is, the 
film is as thick as the particles can hold, the water 
would pass right through the soil and connect with 
the standing water below. This, of course, is sel- 
dom the case in dry-farm districts. In any soil, 
excepting one already saturated, the addition of 
water will produce a thickening of the soil-water 
film to the full descent of the water. This imme- 
