TREES AND SHRUBS 219 



trees is so difficult to determine that the resistance of trees 

 is a much more uncertain matter to determine than it is 

 for the smaller cultures. 



Fruit trees and shrubs which might tolerate large quanti- 

 ties of alkali frequently do not give satisfaction because the 

 quality of the fruit is injured by certain kinds of alkali. 

 This is especially true of the more delicately flavored 

 fruits, such as the peach. In case there is a very ap- 

 preciable quantity of alkali in the soil it is usually better 

 to grow the more resistant forage or grain crops until 

 the land has been reclaimed for fruit. 



Date palms are the most resistant of fruit trees and per- 

 haps the most resistant of cultivated plants. They are 

 unfortunately not adapted to the alkali lands of the United 

 States with the exception of certain of the southwestern 

 regions. The date palm has been known to grow in the 

 presence of 30,000 to 40,000 parts per million of alkali, 

 largely sodium chloride. Where there are layers of soil 

 containing only 6000 to 10,000 parts per million, this 

 palm will produce abundant crops even where the sur- 

 rounding or surface soil contains enormous quantities of 

 alkali. There is no apparent injury where the soil con- 

 tains no more than 5000 parts per million of the white 

 alkali, although where black alkali is encountered the 

 resistance is less. About 600 parts per million of sodium 

 carbonate, 5000 parts per million of sodium chloride, and 

 20,000 to 50,000 parts per million sodium sulphate have 

 been successfully withstood. Palm groves are found 

 flourishing where the upper soil contains 15,200 parts 

 per million of alkali and the surface of the ground is white 

 with alkali. The quality of the fruit is apparently not 

 greatly impaired even where the alkali, which is about 

 one-half sodium chloride, reaches a concentration of 10,000 

 parts per million. 



