110 CAMPBELL'S SOIL CULTURE MANUAL 



surface and the surface is kept loose. As soon as the rain 

 comes in contact with the moist earth below it readily 

 percolates down through the fine soil. In fact the soil 

 that is moist for three or four feet down will dry off on the 

 surface much quicker than soil that is dry underneath 

 because of more rapid percolation. The slowest soil to 

 take the rain waters is the dry soil with a firm surface. 



Again considering the water-holding capacity of the 

 soil, and recognizing a marked difference in the amount 

 of the water held by the fine shot shown in our illustration, 

 we more clearly grasp the value of adding well rotted 

 manures to the soil of the western prairies and the fur- 

 ther importance of having it thoroughly mixed into the 

 soil. The manure when decomposed very materially adds 

 to the number of minute particles and further increases 

 the water-holding capacity. The manure question is fully 

 considered in a chapter by itself, and should be very care- 

 fully studied for its relation to the moisture question is 

 broad; therefore, it is one that means much to the semi- 

 arid country. 



