United States Dtet^ettt W Agriculture, 



BUREAU OF Sto$-ili$jfi&ff!ATt NO. 10. 

 MILTON WHITNEY, Chief of Bureau. 



THE USE OF ALKALINE AND SALINE WATERS FOR IRRIGATION. 



During the summer of 1902 a representative of the Bureau of Soils 

 visited the oases of the Oued Rihr country in the Desert of Sahara in 

 Eastern Algeria. In these oases artesian waters carrying very large 

 quantities of soluble matter are used successfully for irrigation. From 

 the information gathered there, and from experience in this country, it 

 seems that the amount of soluble matter allowable in an irrigation water 

 has been greatly underestimated by American writers, and that many 

 sources of water which have been condemned can be used with safety 

 and success, provided the proper precautions are taken to prevent the 

 accumulation of the salts. As the precautions are those which should 

 be taken by every irrigator, even if pure water is used, it seems an 

 important matter to bring before the American people the methods in 

 use in the Sahara. 



The staple crop grown by the Arabs in the oasis country is the date, 

 the fruit of a palm tree known to be one of the plants most resistant to 

 alkaline or saline conditions of the soil, but in addition to this consid- 

 erable quantities of the deciduous fruits, garden vegetables, and alfalfa 

 are produced for home consumption. 



Some of the vegetables successfully grown are those considered sensi- 

 tive to alkali, and yet they were being irrigated with water containing 

 in some instances as much as 800 parts of soluble salts to 100,000 

 parts of water, sometimes as high as 50 per cent of the salts being 

 sodium chloride. 



The limit of concentration for irrigation water in the United States, 

 even where only the most resistant field crops are to be grown, has 

 been placed by some authorities at 30 parts sodium chloride (common 

 salt) or sodium carbonate (black alkali), and at from 170 to 300 parts 

 of the less harmful salts, per 100,000 of water. The Bureau of Soils, 

 however, several years ago insisted that water of a somewhat higher 

 salt content might be used if the soil had good natural drainage, or 

 artificial drainage were supplied, and the methods of irrigation were 

 modified to suit the different conditions. Thus in 1899 1 the following 

 statements were made after a study of soils and alkali conditions in the 

 Pecos Valley, New Mexico : 



Next to the ownership of the land and the labor questions, the most important 

 cause of the trouble in the larger portion of the Pecos Valley is the high salt con- 

 tent of the irrigation water, especially in certain seasons. 



At Roswell the principal water supply contains about 76 parts of soluble mat- 

 ter in 100,000 parts of water. At Hagerman this is increased to about 200 parts ; 

 at Carlsbad, to 240 parts ; at Florence, to 280 parts ; Red Bluff, 316 parts ; at 

 Pecos City, Tex., to 400 parts; and below Pecos City to over 500 parts. Five 



!Rept. 64, Field Operations, Division of Soils, 1899. 



