106 THE DATE PALM. 



content of the artesian water is no less than 640 parts per 100,000, and 

 after subtracting gypsum there remain 434 parts per 100,000 of harmful 

 alkali 0.434 per cent, or 250 grains to the gallon. At Ourlana, 

 Algeria, very extensive and flourishing plantations are irrigated from 

 a flowing artesian well (Puits Desveaux), where the water contains 635 

 parts per 100,000 of soluble salt and 403 parts per 100,000 of harmful 

 alkali. 



The Colorado River water is better than that used to irrigate the 

 famous Salt River Valley of Arizona, and has the advantage of having 

 the lowest alkali content in summer, whereas just the reverse is true 

 of the Salt River water (see p. 99). 



The water of the Colorado River carries, both in solution and in 

 suspension as tine silt, fertilizing materials of considerable value, con- 

 sisting principally of potash, nitrogen, and phosphoric acid. The 

 soils of the Salton Basin are at present so rich that they do not need 

 the fertilizers thus carried to the land by the irrigating water, but 

 such fertilizing substances deposited by the water will serve to keep 

 up the fertility in the future even under heavy cropping. Even 

 now the phosphoric acid brought by the Colorado River water (see 

 p. 114) is doubtless decidedly beneficial to the soils of the Salton Basin, 

 which contain but very small amounts of this very necessary plant food. 



SOIL CONDITIONS IN THE SALTON BASIN. 



The soil conditions existing in the greater part of the Salton Basin 

 are shown by Means and Holmes, of the Bureau of Soils, a who made 

 surveys in 1901 covering some 108,100 acres lying between the New 

 and the Salton rivers (fig. 10 and PI. Ill), comprising the larger part 

 of the basin as yet put under irrigation. This area is shown on 

 Plate III. The same classes of soils and the same general condition of 

 alkalinity prevail over the greater part of the Salton Basin. 5 



In the portion of the basin surveyed by Means and Holmes five 

 types of soils were recognized. The areas occupied by these types 

 are shown in Table 38. 



Circular 9, Bureau of Soils, January, 1902, and Field Operations of the Bureau of 

 Soils, U. S. Department of Agriculture, 1901, pp. 587-606, map 29. 



& The University of California also investigated the soil conditions in the Salton 

 Basin, and in February, 1902, published a valuable report on this region (Snow, 

 Frank J., Hilgard, E. W., and Shaw, G. W., Lands of the Colorado Delta in the 

 Salton Basin, Bui. 140, Cal. Agr. Exp. Sta., pp. 51, with supplement by Joseph Burtt 

 Davy, The Native Vegetation and Crops of the Colorado Delta of the Salton Basin, 

 April, 1902, pp. 8) . 



