THE WATER IN THE SOIL 19 



right of it; the third about three quarters of an inch 

 above the second and a httle to the right of it. Make a 

 cup-shaped hole in the top of the soil and add water until 

 it begins to flow from each of the holes in the side of the 

 can. 



Conclusion. ■ — From which hole did the water first 

 begin to flow ? Let the lowest hole represent the bottom, 

 the middle one the side, and the highest one the top of the 

 tile. Does this not mean that the water must fill the soil 

 from the bottom upward, then work its way laterally 

 through the soil until it reaches the tile, entering the 

 joints at the bottom? From here it flows out to the 

 drainage ditch or natural outlet. Trace a given amount 

 of water from a rain cloud through a tile-drained soil to 

 the creek or river. 



12. Three Kinds of Water in the Soil. — We have just 

 been studying how a certain amount of water escapes 

 from the soil. This water, which moves through the 

 soil and drains away, is known as free, or gravity, water. 

 It is of no benefit to plants whatever. On the other hand, 

 it is an absolute detriment to them. When this gravity 

 water has drained away, there remains a tiny film about 

 each soil particle, known as film, or capillary, water. This 

 is the moisture, of which the plant makes use. There is, 

 however, still another kind of moisture, known as hygro- 

 scopic moisture. It is the water which may be driven off 

 by heating the soil to a high temperature after it is thor- 

 oughly air dried. It plays no part whatever in plant 

 growth. 



EXERCISE 7 



Object. — To determine the percentage of each kind of 

 water in a soil. 



Procedure. — Secure a tomato can or a tin can with a 



