22 Fruit-growing in Arid Regions 



regions is due to the gradual rise of the level of water in 

 the ground, and which is caused by excessive irrigation. 

 Under these conditions any soil that is at all retentive 

 of moisture may become wet. This is especially true of 

 the low-lying land where the adjacent higher lands are 

 irrigated. 



A rational use of water in irrigation will, of course, lessen 

 the damage by seepage, and by conservative and intelli- 

 gent drainage, practically all seeped lands should be re- 

 claimed. Moreover, in the case of fruit regions, the high 

 price which such land brings will usually make drainage 

 profitable. 



Alkali 



In brief, alkali land is always seeped land, or at least the 

 efflorescence of alkali upon the surface of the ground can 

 occur only where the evaporation of water takes place. 

 It is rare indeed that soil in the virgin state contains 

 enough of these salts to be harmful to the ordinary orchard 

 and farm crops. 



The name alkali is comprehensive, and includes the salts 

 of sodium, potassium, magnesium, and calcium. The so- 

 called black alkali, sodium carbonate, occurs but rarely 

 in the inter-mountain fruit regions. These substances are 

 all more or less soluble, and may occur in any soil forma- 

 tion. Originally they were constituents of certain rocks, 

 particularly feldspars, from which they are dissolved. 

 They are taken into solution and carried to the fields 

 during irrigation, where they may be deposited by evapora- 

 tion. But such deposits rarely occur in sufficient amounts 

 to be harmful; therefore it may be safely assumed that 

 alkali never collects in excessive quantities in cultivated 



