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AGRICULTURAL ECONOMICS 



causes of decline that are not well understood. The evidence thus 

 far available indicates that the deterioration of irrigated land may be 

 due in some cases to obscure diseases of the plants or to some derange- 

 ment of the processes of nutrition rather than to a lack of fertility, as 

 that term is understood in agriculture under rainfall. Whether or 

 not there is inherent in irrigation agriculture a set of adverse conditions 

 other than those related to the rise of alkali remains to be determined. 

 In any event there is reason for believing that many of our irrigated 

 districts may long continue in a high state of productivity because the 

 available land so much exceeds the available water that when any 

 particular tract of land becomes unproductive the water may be 

 carried to new land at small additional expense. But such shifting 

 of water to new land must often result in some individual hardships 

 where a farmer has all his capital invested in the land that is aban- 

 doned. 



NOTE. The Thirteenth Census (Vol. V, p. 846) gives the follow- 

 ing figures concerning irrigation development in the United States: 



EDITOR. 



39. NEED OF IRRIGATION IN THE HUMID REGION 1 

 BY MILO B. WILLIAMS 



The people of this country have come to associate the practice of 

 irrigation with the growing of crops in localities where the scanty 

 rainfall produces only desert plants. But in fact supplemental irri- 

 gation is not only possible but needed in the growing of the more 

 valuable crops throughout many portions of the humid region. 



A climate having an annual rainfall of 20 inches or more is gener- 

 ally regarded as humid, for where this amount of rain is fairly well 



'Adapted from "Supplemental Irrigation in the Humid Region," Yearbook 

 of the Department of Agriculture, 1911, pp. 300-20. 



