34 HINTS ON SOILS AND FERTILIZERS 
of water from which the plant takes its mois¬ 
ture, and also through which it derives its 
plant food elements. Ordinarily, one would be 
led to the conclusion that the low pieces of 
land, which are wet the longest period of the 
year, should produce the greatest yields, due to 
the dependence of crops on the water supply. 
But it has just been stated that the plant does 
not use this free water for its supply, but rather 
the capillary moisture. Let us now examine 
this capillary moisture, as it is an exceedingly 
interesting process. 
There is usually a water line in soils that is 
some distance below the surface of the soil. 
This water, existing in the free state, has a 
tendency to work upwards, at this particular 
point. Its movement upwards is not unlike 
the action of kerosene in the wick of a lamp. 
The water surrounds the fine soil particles, 
forming a thin film of moisture around the sur¬ 
face of these particles. The moisture does not 
stay in one place, but constantly moves over the 
surfaces of these soil particles to a drier point. 
The reason for this constant movement of film 
water is this: Near the surface of the soil, 
especially if the soil is a compact hard mass, 
and lacking cultivation, there is a constantly 
giving off of moisture, either through evapor¬ 
ation from the surface of the soil, or by giving 
up soil moisture to the little rootlets that we 
studied about in a previous chapter. As a re¬ 
sult, the upper portion of the plowed area of 
the land is constantly drawing upon the mois¬ 
ture supply. The tendency of the capillary 
water is to constantly move to the drier sec- 
