Dry Farming and Irrigation 



161 



International Harvester Co. 



FIG. 126. Pumping water for irrigation. A portable gasoline engine furnishes 

 the power. In parts of China and Egypt, human power is still used for such 

 work. 



changes to gases and escapes into the air. Therefore, 

 to keep up the supply of humus, it is well to plow 

 under, when possible, such waste crop materials as straw. 

 It should be kept in mind, however, that one can, in 

 dry regions, get an excess of vegetable matter into the 

 soil. The soil will then be too light and it will easily 

 dry out and blow away. 



Irrigation. Water to irrigate with is often pumped, 

 either from wells or streams (Fig. 126). Gasoline 

 engines, electric motors, or windmills are used to operate 

 the pumps. Windmills are slow, and they are unreliable 

 on account of the irregularity of wind. Gasoline motors 

 give plenty of power but require much more attention 



Supplying 

 humus 



Sources of 

 water for 

 irrigation; 

 pumping 



