IRRIGATION AND DRY FARMING 17 1 



from which the water is taken will dry up during the season 

 when water is needed, reservoirs are built so that a greater 

 part of the winter rainfall may be used. Quite a number of 

 methods of applying water by irrigation are in use, but 

 those most common are sprinkling, flooding, and by 

 furrows. 



Sprinkling. Of the three methods named, this one most 

 nearly resembles the method by which nature furnishes 

 water to growing plants. But in spite of this fact, sprinkling 

 is no doubt the poorest of the three methods. To apply a 

 sufficient amount of water at one time by this method re- 

 quires a very slow application for a long time, for if applied 

 too rapidly, the ground, if it is not sandy, becomes packed 

 and hardened. In this condition air, which the plant needs, 

 cannot get through the soil, and the roots also find it difficult 

 to push through it. There is also very rapid evaporation 

 from the surface unless the soil is stirred soon after the 

 sprinkling. This results in great waste of moisture, and a 

 second sprinkling is necessary in a short time. If practiced 

 in regions where there is no rainfall in summer, it must be 

 repeated often and a sufficient amount put on to wet the soil 

 to a considerable depth. Otherwise the plant will develop 

 a shallow root system and will be completely dependent upon 

 water thus applied all through the growing season. On the 

 other hand, plants which have a deep-rooting system are often 

 able, after a while, to draw their needed supply of moisture 

 from the water in the subsoil. 



Flooding. This method is used only where an abundance 

 of water can be had and where the land to be irrigated is 

 quite level or can be made so. As in the case of sprinkling, 

 there will be rapid evaporation unless the surface of the 



