COMPOSITION OF ALKALI, SALTON BASIN. 



113 



The following table shows the composition of the alkali in a few 

 surface crusts and soils in the Salton Basin. The analyses are some 

 of those given by Means and Holmes. a 



TABLE 44. Theoretical percentage composition of alkali in soil about Imperial, Col. 



The alkali of the Salton Basin is of the same type (" white alkali") 

 as that of the Sahara Desert in southern Algeria, since in both regions 

 a large excess of gypsum is present in almost all cases, which pre- 

 vents the formation, under ordinarily good conditions of culture and 

 drainage, of any dangerous amount of the very harmful alkaline car- 

 bonates. The Salton Basin samples differ considerably from those 

 from the Sahara in showing rather large percentages of sodium nitrate 

 in the surface crusts, which is entirely lacking in the surface crusts or 

 soils from the Sahara. However, only very small quantities of nitrates 

 occur below the surface crust in the soils of the Salton Basin, unless 

 the soils are so alkaline as to preclude all agriculture. The Salton 

 Basin soils often show considerable percentages of calcium chlorid, 

 wanting in Sahara soils. Salton Basin soils contain much larger per- 

 centages of potassium chlorid and sodium bicarbonate and a larger 

 proportion of chlorids and less sulphates than do the Sahara soils 

 examined 



The Salton Basin alkali is slightly more dangerous to crops than that 

 of southern Algeria, because of the larger proportion of chlorids, and 

 because of the presence, in many cases, of considerable amounts of 

 sodium bicarbonate, which, if the land is watered excessively and 

 badly drained, may be converted into the very harmful sodium 

 carbonate. 



Means and Holmes. Soil Survey around Imperial, Cal. Field Operations of the 

 Bureau of Soils, U. S. Department of Agriculture, Third Report, 1901, p. 601. 



13529 No. 5304 8 



