SOIL IMPROVEMENT 91 



inches, crops often suffer for lack of rain during the growing season. 

 Droughts are becoming more frequent and prolonged in many 

 of the eastern states on account of the destruction of the forests, 

 which are Nature's reservoirs of moisture. 



Irrigation. Crops are protected against scanty or uneven rain- 

 fall by irrigation. Irrigation is a system of distribution of water 



IRRIGATING ALFALFA BY THE FURROW SYSTEM 



On this western field, alfalfa is irrigated after each cutting; there are sometimes as many 

 as six cuttings a year. 



to crops, by means of canals and reservoirs connected with streams 

 or lakes. Irrigation is not a modern invention. It was practiced 

 in Egypt and in India thousands of years ago. When the Span- 

 iards first came to America, they found Mexico and Peru irrigated 

 by vast systems of canals. 



Our government is spending millions of dollars in irrigating 

 the arid states. Much of this land was once a barren waste dotted 

 with stunted sagebrush and cacti, the home of prairie dogs and 



