86 



THE DATE PALM. 



would be counted too alkaline to use for irrigation anywhere outside of the Sahara, 

 though at Chegga it is the only water used to irrigate a flourishing date orchard 

 planted on soil originally very alkaline, but which has been improved, even while 

 being irrigated with such water, by means of drainage ditches into which the excess 

 of alkali has been washed. Figure 1 on Plate XVI shows the appearance of these 

 palms growing where alkali can be seen at the side of the irrigation ditches. Figure 

 2 on the same plate shows a reclaimed area where Saharan alfalfa was growing. 



Station No. 1 at Chegga was in the date plantation in a very alkaline spot, close to 

 an offshoot that had failed to grow, probably because of the excess of alkali in the 

 soil. The subsoil was taken from the side of the drainage ditch, some 18 feet away, 

 and may not represent the true state of the subsoil where the surface soil and crust 

 were taken. 



The crust shows the following amounts of alkali soluble in an excess of water (20 

 times weight of soil sample): 



TABLE 19. Per cent of alkali soluble in excess of water in surface crust from, Station No. 1, 



Chegga, Algeria. 1 



The soil shows the following amounts of alkali: 



TABLE 20. Per cent of alkali in soil of date plantation, Station 1, Chegga, Algeria. 1 



1 Mr. Seidell's original analyses of the samples from this station are as follows: 



aThe Chegga water contains over 374 grains of alkali per gallon; whereas 40 grains is usually given 

 as the limit for drinking water, and anything above this is considered doubtful for irrigating pur- 

 poses, unless the salt in solution is gypsum. Even excluding gypsum, the Chegga water still con- 

 tains 250 grains to the gallon, whereas the water of Lake Elsinore, which so disastrously affected the 

 orange groves on which it was used near Riverside, Cal., contained only 84 to 116 grains per gallon. 

 (See Report, California Agricultural Experiment Station, 1897-98, pp. 99-113 and 126-130.) 



