100 THE DATE PALM. 



As was noted on page 86, water as alkaline as this is without any 

 direct effect on the date palm and could be injurious only by leading 

 to the accumulation of alkali in badly drained soils after many years 

 of heavy irrigation. 



A sample of surface crust from an alkaline spot south of Tempe, 

 Ariz. (sec. 3, T. 1 S., R. 4 E.), near where the Cooperative Date Garden 

 (Pis. XXI, XXII, and fig. 6, p. 36) is located, shows the following 

 relative amounts of alkali soluble in excess of water (50 grams of soil 

 to 1,000 grams of water), which may be compared with the analyses 

 of crusts from the Sahara and from the Sal ton Basin (p. 134) : 



TABLE 36. Percentage composition of alkali (soluble in excess of water) in surf ace crust 



from near Tempe, Ariz. a 



Calcium sulphate 1. 56 



Magnesium sulphate 3. 04 



Sodium sulphate 8. 98 



Sodium chlorid J 59. 72 



Potassium chlorid 12. 18 



Sodium carbonate 4. 14 



Sodium bicarbonate . . .10. 38 



Total per cent of weight of soil 2. 56 



The surface soil (1 to 12 inches in depth) from the same station 

 shows the following amounts of alkali stated in per cents of the weight 

 of the soil: 



TABLE 37. Per cent of alkali in surface soil from Tempe, Ariz. & 



Calcium sulphate 0. 06 



Magnesium sulphate 06 



Sodium sulphate 22 



Sodium chlorid 1. 53 



Potassium chlorid -. 23 



Sodium carbonate 06 



Sodium bicarbonate . . .32 



Total 2. 48 



It must be remembered that in. the Cooperative Date Garden at 

 Tempe the roots doubtless reach a subsoil containing much less than 

 this amount of alkali. Most of the alkali spots in the Salt River 

 Valley can be planted profitably to date palms if care be taken in irri- 

 gating (see chapter on drainage, p. 50). Near the date garden alfalfa 

 was killed by the rise of alkali a few years ago, and even pear trees 

 showed evident signs of distress, while a date palm growing alongside 

 was entirely unaffected by the alkali. 



Analyses quoted from Thos. H. Means, Field Operations of the Bureau of Soils, 

 Second Report, 1900, p. 320. 



& Calculated from an analysis reported by Means, 1. c., p. 320. 



