172 



IRRIGATION AND DRY FARMING 



ground is stirred soon after the water is put on. A great 

 disadvantage in this method is the long time necessary in 

 order to put on enough water to do any good. This is neces- 

 sarily so because of the fact that the air in the soil prevents, 

 after a little, the rapid soaking up of the water, as the in- 

 creasing weight of the water prevents the escape of the air 

 in that direction. This method might be used to advan- 

 tage in connection with the system of dry farming described 

 later in this chapter. 



FIG 98. Furrow System of Irrigation. 



The Furrow Method. Of all the methods of irrigation, 

 the furrow method is most commonly used. One of its 

 chief advantages lies in the fact that by it the subsoil be- 

 comes so soaked that a deep-rooting system is developed. 

 By this method, water reaches the surface of the ground 

 only by capillary attraction (page 14), hence the soil does 

 not become so packed as to shut out the air and hinder the 

 roots from growing downward. 



