Timely Hints for Farmers. 281 



were in part composed of carbonate of soda, or "black alkali," 

 but for the most part chiefly consisted of chloride and sulphate of 

 soda. Wells drawing their supply from the underflow of moun- 

 tain washes are, on the other hand, of far purer character. A 

 sample from the underflow of Agua Fria contained but 30 parts 

 of salts in 100,000 of water; while the University well near Tuc- 

 son, probably fed by the drainage from the mountains to the east- 

 ward, contains only 26 parts. 



The artesian waters of Southern Arizona form a class by 

 themselves, being uniformly more or less black alkaline, but 

 varying widely in the amount of salts in solution. 



The following is a statement of analyses of the least and the 

 most saline artesian waters thus far examined : 



The amounts of the various soluble compounds proving in- 

 jurious to crops depends upon the nature of the compound, the 

 kind of soil, and the crop grown. Of the common soluble com- 

 pounds, carbonate of soda is most injurious, common salt next, 

 and sulphate of soda least. 



Speaking of barley, Dr. Hilgard of the California Station, 

 states that, while a full crop was obtained on land containing 25,- 

 440 pounds of soluble salts per acre in the surface four feet, it re- 

 fused to grow in soil containing 32,480 pounds. The same 

 author also remarks that leguminous plants (clovers, beans, etc. ), 

 crucifers (mustard, kale, etc.), and citrus trees are more sensitive 

 to alkali than barley. On the other hand, Bermuda and certain 

 salt grasses, the salt bushes, pomegranate and pear, the date 

 palm, and certain root crops (including sugar beets), will thrive 

 in soils containing much greater quantities of salts than barley 

 will tolerate. 



Now, reckoning on three acre-feet of water a year for mixed 

 farming, at least which is necessary in Southern Arizona, a sup- 



