HOW WATER IS HELD IN THE SOIL 205 



e. 1609 : 38-40. Importance of Moisture. 

 /. 1611 : 34-35. What Water Does in Soils. 

 g. 1611 : 55-59. Plant Food in Soil Water. 



147. How WATER is HELD IN THE SOIL 



In Section 145, Texture of the Soil, we noted that the 

 smaller the particles were, the more surface they had, and the 

 larger amount of water they could then hold. Water is held 

 in the soil by actual porosity, just as water is held in a sponge; 

 it is also held by capillarity, in the same way that oil travels 

 up a lamp-wick. See Section 118, Capillarity. Finally, it is 

 held in a chemical method, forming almost a compound with 

 the soil. This is called hygroscopic water. See Section 122, 

 Hygroscopic Salts. The wise farmer makes use of these 

 characteristics in order that his crops may receive sufficient 

 water. This will be considered under Tilling the Soil, Sec- 

 tions 148-149. 



The water which merely fills the larger spaces in the soil 

 rapidly passes away, soaking into the earth, and does not enter 

 much into the food supply of plants. The capillarity causes 

 the lower water to creep up and keep the upper layers con- 

 stantly moist. The hygroscopic water is so closely bound to 

 the soil that the soil may feel perfectly dry, although contain- 

 ing considerable moisture. Hygroscopic water, then, is of 

 no value whatsoever to the farmer. 



References : 



1. 1503 : 91-92. How Water is Held in the Soil. 



2. 1601 : 157-162. Capacity of Soils to Hold Water. 



3. 1605 : 79-81. Relation of Size of Particles to Water. 

 a. 1602 : 17-20. The Soil and Soil Water. 



6. 1603 : 10-14. The Moisture of the Soil and How it Moves, 

 c. 1604 : 128-129. The Movements of Water in the Soil. 



