324 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 



lesser amounts, while a much larger proportion contains intermediate 

 quantities of salts. Fortunately, however, a very large proportion 

 of the irrigation water is highly satisfactory in quality. 



It has been found that a considerate number of citrus groves 

 located in several districts in California have already been severely 

 injured by alkali and that a large percentage of the injury is due to 

 the irrigation water. 



The comments of Hilgard made in 1900 relative to the use of saline 

 irrigation water may be appropriately quoted at this time : 



Means and Gardner 7 have called attention to the fact that exces- 

 sively saline irrigation waters have been applied to the soils of certain 

 portions of the Pecos Valley, New Mexico, and that severe damage has 

 been produced as a result. In discussing this problem in 1899, they 

 said: "The soils were shown to contain originally only small quantities 

 of alkali salts in their natural state, but at present there are areas 

 containing great quantities of such salts. The presence of this alkali 

 may, in nearly all cases, be attributed mainly to the salt which is 

 contained in the irrigation water. . . . The character of the water is 

 the most serious difficulty in the way of profitable irrigation. To 

 develop a new supply of water would be an engineering problem 

 difficult of solution. The use of the present supply is attended with 

 possible loss of crops, especially where the most favorable conditions 

 do not exist." 



Forbes 8 showed that the irrigation waters of the Salt River and 

 other valleys of Arizona are supplying large amounts of salts to the 

 soils. From soil analysis he found that the salt content of the soil 

 had been materially increased in consequence of applying saline 

 water. 



G Calif. Agr. Exp. Sta. Bull. 128 (1900), p. 30. 



It would hardly seem necessary to emphasize specially, the danger incurred in 

 irrigation with waters containing unusual amounts of soluble salts; since ordinary 

 common sense clearly indicates the impropriety of increasing the saline contents 

 of soils already charged with them, by the evaporation, year after year, of large 

 masses of saline water. Yet experience has shown that the eagerness to utilize 

 for irrigation whatever water happens to be convenient to good lands, often over- 

 comes both that sense, and warning, given by the published analyses of such 

 waters. Without specifying localities, it may bo said that great injury has already 

 been done in California by the disregard of obviously needful caution in this 

 respect. The very slight taste possessed by glauber salt and salsoda does not 

 adequately indicate their presence, even when in injurious amounts; so that fre- 

 quently a chemical test of the waters is the only definite guide. 



" A Soil Survey of the Pecos Valley, New Mexico. U. S. Dept. Agr., Report 64, 



pp. ;?<>-7<5. 



* The River Irrigating Waters of Arizona Their Character and Effects. Ariz. 

 Agr. Exp. Sta. Bull. 44, 1902. 



