AGRICULTURE UNDER IRRIGATION 473 



irrigation. It seems certain that as soon as sound growth 

 will allow all the water, especially in the arid regions, will 

 be stored and diverted for purposes of irrigation. 



The mighty dams and endless lines of canals will soon 

 be completed. If the work has been well done, we shall 

 need only to maintain in a sound condition the structures 

 of steel and rock and cement and wood and earth that 

 have been built. The overshadowing problem then, as it 

 is the great one now, will be that of using the water in 

 the best manner for the production of crops. Two- 

 headed is this problem: First, the water must be made to 

 produce the largest total yield of crops for the support of 

 man; second, the practice of irrigation on a given area of 

 land must be made continuous and increasingly desirable. 

 To this double problem is this volume devoted. 



270. The spirit of irrigation. Our modern knowledge 

 is teaching the methods whereby irrigation may be made 

 to produce the maximum crops for each unit of water used. 

 All irrigation advocates are rapidly accepting the new 

 truth. The very spirit of the conquest of the desert is 

 that men shall be benefited many men; the more men 

 the better. The largest possible area of land must be 

 reclaimed by the stored waters, even if the acre-yield 

 does not reach so high an average. 



271. No essential difference between irrigation- and 

 humid-farming. Our modern knowledge teaches also 

 that there is no essential difference between rainfall- 

 farming and irrigation-farming, except in the manner in 

 which water is applied to the soil. Every argument against 

 the permanency of irrigation-farming may be urged 

 against rainfall-farming; and every argument for the per- 

 manency of rainfall-farming may be used with equal force 

 in behalf of irrigation-farming. The everlasting relation- 



