276 Irrigation and Drainage 



of any other than samphire, saltwort, and the like, 

 and that even these cannot thrive when the salt 

 becomes as high as 5 per cent. 



Deherain concludes, from his studies in France, 

 that while soils kept very moist may produce crops 

 even when 2 per cent of salt is present, yet if the 

 soils dry out badly they become sterile with no more 

 than 1 per cent present. Gasparin has maintained, 

 however, that while soils containing .02 per cent of 

 salt may produce good crops of wheat, .2 per cent 

 is more than this crop can bear. 



Speaking, next, of the alkali salts of arid climates, 

 we may cite some of the data procured by Hilgard in 

 his extended and careful studies of the alkali problems 

 of California. At their Tulare Experiment Station, 

 he gives both the amount and the distribution of 

 soluble salts in the surface 18 inches of soil where, 

 in one case, barley grew to a height of 4 feet, and in 

 another the amounts of the salt were so great that 

 this crop would not thrive. The data which we give 

 in tabular form have been read from his plotted curves, 

 hence the values must be regarded as not quite exact. 



Table showing amount and composition of alkali salts in parts per 100 

 Taken September, 1894, Tulare Experiment Station, California 



Ground upon which barley Ground upon which barley 



grew 4 feet high did not grow 



Depth in Sodium Sodium Com'n Total Sodium Sodium Com'n Total 



3-in carb'ate sulphate salt soluble carb'ate sulphate salt soluble 



sections Na2 co 3 Na 2 SO 4 NaCl salts Na 2 CO 3 Na 2 SO 4 NaCl salts 



