144 MOVEMENT OF SOLUBLE SALTS 



completely to the surface of a column of soil 150 cm. in 

 height supplied with water at the bottom. Hilgard as 

 well as Puchner (28) and others have noted a migration 

 of salts upward and downward as the moisture changed 

 places. 



The latter experimenter, using quartz sand, loam, 

 and rich humus soils, found the movement to depend 

 somewhat on the chemical and physical properties of the 

 soils. Powdery soils allowed the salts to move more 

 readily than crumbly soils. Kossovich (20) reports a 

 greater movement on a loess clayey soil than on a sandy 

 soil and that sodium chloride hastened the rise of water 

 while sodium carbonate impeded it. IV is probable that 

 the differences both in nature of the salts and their con- 

 centration so often noticed in fields containing alkali are, 

 in part at least, due to changes in the nature of the soils 

 which in turn modify the rate of capillary action. In 

 studies of the movement of moisture, Briggs and Lapham (2) 

 conclude that " concentrated or saturated solutions of all 

 salts materially diminish capillary action," but that in 

 dilute solutions the neutral salts had very little influence 

 on capillary action. They found sodium carbonate to have 

 a greater influence on capillarity than the neutral salts. 



The extent of the fluctuation of salts upward and down- 

 ward under irrigation in the field has not been determined 

 with any degree of accuracy. Hilgard considered the 

 movement to be mostly in the top four feet. Considering 

 the ease with which the salts move with the water and 

 from observations of the movement of soluble salts with 

 irrigation water when no alkali was present (11), it is very 

 probable that the salts are frequently moved to great 

 depths where not prevented by impervious soils or by a 

 water-table. Investigations show that water is seldom 



