238 IRRIGATION PRACTICE 



farming. They are twin sisters. Upon them rests the 

 responsibility of reclaiming the two-thirds of the earth 

 which receive an annual rainfall of less than 20 inches. 

 Newell estimates that under a perfected system of water 

 storage, it is probable that not more than one-tenth of 

 this vast arid region will be reclaimed by irrigation. The 

 remaining nine-tenths must be reclaimed, if at all, by the 

 methods of dry-farming. On the irrigated lands will be the 

 great cities and the bulk of the population, but surround- 

 ing them will be the great dry-farm empires, the products 

 of which will help support the people on the irrigated 

 tracts. Since, in any country, the supply of irrigation 

 water is adequate to cover only a small fraction of the 

 arid lands, it is important to learn every method whereby 

 irrigation water may be made to render a high duty and 

 to cover more land. The most promising method for 

 accomplishing this result is the introduction into irriga- 

 tion practices of methods whereby the natural precipita- 

 tion may be conserved in the soil. That is, thorough and 

 deep plowing in the fall, and frequent and deep cultiva- 

 tion, should be made part and parcel of irrigation practices. 

 When, in connection with this thorough tillage, irrigation 

 water is applied in smaller quantities, so that larger returns 

 may be obtained for each unit of water, it is not unlikely 

 that the irrigated area may be increased three- or four- 

 fold. From the beginning, therefore, the irrigation farmer 

 should familiarize himself with the methods of dry-farming 

 and apply them so far as may be possible in the develop- 

 ment of a high duty of the available irrigation water. 



150. Dry-farm homesteads. The dry-farming areas 

 are often at considerable distances from large water sup- 

 plies, although small springs or streams or subterranean 

 waters are usually within reach. In some cases water 



