8o ELEMENTARY SCIENCE 



The amount of water transpired by growing crops has 

 frequently been estimated. It has been found that in 

 the production of one ton of well-dried hay, over three 

 hundred tons of water are used. Corn which produces 

 fifty bushels to the acre uses, during its life, an acre of 

 water ten inches deep. 



Irrigation. Agriculture does not depend for water on 

 rain alone. Doubtless you have heard of irrigation. It 

 is the process of watering land by artificial means. It 

 is an ancient art. It was practised in the Nile Valley in 

 the days of the Pharaohs, even before the pyramids were 

 built, and even to-day we find highly developed irrigation 

 systems built and operated by savage tribes. They are 

 found in mountainous regions where agriculture requires 

 the building of terraces as well as the conveyance of water 

 by ditches. 



The modern development of irrigation in the United 

 States is very extensive. We have in the West vast areas 

 of desert land; the climate is excellent for agriculture and 

 the soil is usually fertile. All that is lacking to make 

 these lands "blossom as the rose" is water; water supplied 

 throughout the growing season. To thousands of such 

 acres in some Western States, water has been supplied. 

 It has been supplied by ditches from rivers and from 

 mountain reservoirs, and now some of this irrigated land 

 is the most fertile and valuable land that we have; often 

 when developed it sells for more than a thousand dollars 

 an acre. In Arizona and California you may see orange 

 groves, or rich and beautiful fields of alfalfa, while just over 

 the fence from them is the desert, whose only plants are 

 sagebrush and cactus and the like. The soil is the same. 



