98 



THE DATE PALM. 



made between this and the common date palm, in the hope of securing alkali-resistant 

 date palms able to mature fruit near the sea in California. 



Through the courtesy of Mr. Thomas H. Means, of the Bureau of Soils, the author 

 is enabled to present the results of the analyses of soils from date-palm plantations of 

 the Oued Rirh country in southern Algeria secured during the trip he and Mr. Thomas 

 H. Kearney made in 1902 for the Office of Seed and Plant Introduction and Distribu- 

 tion. These soil samples, which were collected after the above pages were writ- 

 ten, were obtained in the same region as those secured by the writer two years 

 previously, and amply confirm the writer's conclusions as to the extreme resistance 

 of the date palm to alkali. Mr. Means' s tabulation is as follows: 



TABLE 35. Resistance of date palms to alkali at four stations in the Oued Rirh country in 

 the Sahara Desert in Algeria. 



This column has been added to Mr. Means's table, and shows the amount of alkali, counting cal- 

 cium sulphate at 0.05 per cent in accordance with the method outlined on p. 74. These sums may 

 be compared with the analyses reported on the preceding pages and with the alkali content of soils 

 determined by the electric method. 



&In regard to the seeming discordance between the results of the determination of the amount of 

 alkali by the electrical and chemical methods, Mr. Means writes as follows: " The apparent discrep- 

 ancy between the total solids as determined by the bridge and by chemical analysis in the samples 

 collected from 13-y< 

 laboratory was colle 



collected from 13-year-old palms at Ourlana is due to error in sampling, for the sample sent to the 

 lected from a different hole from the sample determined by the bridge." 



The amount of harmful alkali is very high in these soils, higher in fact than in any 

 of the soils collected by the writer except at Chegga, Station No. 1, and Fougala, 

 Station No. 1. These newest analyses demonstrate anew the remarkable alkali 

 resistance of this wonderM palm and show that it is perhaps more resistant than 

 the writer's soil samples seemed to indicate, and make his estimates of its probable 

 resistance conservative, to say the least. 



DRAINAGE WATER FROM ALKALINE SOILS USED TO IRRIGATE DATE PALMS IN THE SAHARA. 



It is a remarkable fact, showing the high resistance of the date palin 

 to alkali, that drainage water is used to irrigate date palms even in the 

 Oued Rirh region, where the artesian water is strongly brackish as it 

 flows from the well, and where in addition it must seep through the 

 very alkaline soil before reaching the drainage ditches. Such palms 

 are said to be less vigorous and to yield less fruit. There are several 

 date plantations in the oasis of Tozeur, in the Tunisian Sahara, which 

 are irrigated exclusively by water from the drainage ditches of gardens 



See Yearbook of the Department of Agriculture, 1902, p. 573. 



