THE CONQUEST OF ARID AMERICA 



the fertilizing quality of the annual deposit of river sedi- 

 ment. The partisans of irrigation have made much of 

 this aspect of the matter, asserting that the artificial 

 application of water is itself a means of fertilization. 

 They have asserted the claim, not only where the source 

 of supply, as in the cases of the Rio Grande and the Rio 

 Colorado, is obviously heavily charged with silt held 

 in suspension, but with almost equal ardor in cases 

 where the water flows, a stream of limpid crystal, di- 

 rectly from the mountain-side, or gushes impetuously 

 from the earth in artesian outpourings. 



That the famous river Nile does, indeed, leave a thin 

 deposit of rich soil upon each subsidence of its annual 

 flood our California scientist does not, of course, deny. 

 He proves, however, that this layer of new soil is only of 

 the thickness of common cardboard one-twenty-fifth of 

 an inch and is equal to only about two good two-horse 

 loads per acre. Three times as much stable manure is 

 the usnal dressing for an acre. He truly observes that 

 as the sediment is merely rich soil, thousands of farmers 

 could readily haul and spread such fertilizer upon their 

 land, and would doubtless do so if they could thereby 

 duplicate the phenomenal fertility of the Nile country. 

 He clinches his argument by showing that the neighbor- 

 ing province of Fayoom, in the Libyan Desert, shares 

 the perpetual fertility of the Nile district, though irri- 

 gated only with the clear waters of Lake Moeris ; that 

 the regur lands of the Deccan, in south-central In- 

 dia, have been phenomenally productive for thousands 

 of years, and that the loess region of China, drained 

 by the headwaters of the Yellow river, have been the 

 granary of China for ages. Like the famous Egyptian 



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