CHAPTER II 



THE WATER IN THE SOIL 



A SOIL may be ever so rich in both mineral and organic 

 matter and yet lack water. There can be no crops unless 

 water is added to the soil in the form of rain or by means 

 of irrigation. 



8. How the Soil loses Water. — We may liken the 

 soil to a great sponge, standing ready to receive whatever 

 moisture comes to it. Soils, like sponges, vary in their 

 ability to receive and hold water. Rain or irrigation 

 water received by the soil is lost or escapes in four ways: 



First : it runs off the surface. 



Second: it filters down through the soil and drains 

 away. 



Third : it evaporates from the surface as standing water, 

 or as water which was first taken in by the soil and later 

 worked its way to the surface. 



Fourth : it is taken in by the roots of plants and escapes 

 as water vapor from their leaveS. 



9. The Water which runs off the Surface. — The 

 amount of water which runs off from any soil depends of 

 course upon the amount of rain, the rate at which it falls' 

 and the amount of moisture already in the soil. There i^ 

 another factor, however, greater than any of these; the 

 rate at which the soil can take up water and the capacity 

 of the soil to hold water. Let us prove that this is true. 



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