IMPROVEMENT OF THE SOIL 51 



near rivers and lakes are often irrigated by pumping, 

 where it is not feasible to take the water out in 

 ditches. Where the distance to be lifted is small 

 and fuel chea^), the powerful pumps now in use make 

 this method of irrigation practicable on a large scale. 

 Much of the rice land in western Louisiana and east- 

 ern Texas is irrigated in this manner. In irrigation 

 by pumping the water may be run directly into the 

 ditches, or it may first be stored in reservoirs. The 

 latter is the more usual practice with small pump- 

 ing plants. 



In southern California and some other mountain- 

 ous countries water for irrigation is obtained by 

 drifts or tunnels dug back into the hills until some 

 underground water, channel is tapped. The water 

 runs out of such a well as this by gravity and thus 

 obviates the necessity for pumping. It is, of course, 

 only under exceptional circumstances that this 

 method can be employed, but such a " water mine " 

 may be exceedingly valuable, for in arid regions it 

 is the control of the water supply rather than the 

 ownership of the land that carries the greatest value. 



Whatever the source of the water, there are 

 various methods of applying it to the land. Where 

 the supply is abundant, especially with such broad- 

 cast crops as alfalfa and the small grains, the more 

 usual method is by flooding the entire surface. In 

 order to do this successfully the land must have 

 been carefully prepared before planting and all the 

 minor inequalities leveled down so as to allow of 

 the even flow of the water. Temporary openings 

 are made in the ditch bank and the water is allowed 



