EXPERIMENT STATION BULLETINS. 621 



Effect of Application of Soluble Salts Upon the Concentration of the 

 Soil Solution in the Soil. 



Our present knowledge concerning the effect of application of soluble 

 salts upon the concentration of the soil solution in the soil is extremely 

 unsatisfactory. A great amount of experimental work has been done 

 upon the subject but the conclusions drawn therefrom are not at all 

 concordant. This is undoubtedly due to the fact that there has been 

 no method of attacking the problem directly and consequently the 

 studies had to be conducted indirectly. As a result of this difficulty 

 many of the present views concerning the effect of application of soluble 

 salts upon the concentration of the soil solution in the soil have been 

 deduced from a priori consideration from certain physical laws of 

 solutions and physical projjerties of soils. According to the theory ad- 

 vanced many years ago by Wliitnoy and Cameron, (18), the application 

 of soluble salts such as K('l would probably not increase the concen- 

 tration of the soil solution. They based their theory upon the law of 

 equilibrium of solutions. Their studies with water extracts led them 

 to believe that the soil solution is saturated or nearly saturated in 

 respect to the soil constituents, and the application of such soluble salts 

 with which the solution is already saturated would merely force back 

 the dissociation and thus re-establish equilibrium. The concentration 

 of the soil solution, therefore, tends to remain constant. 



According to the absorption-adsorption theory the concentration of 

 the soil solution may not be increased by the application of soluble 

 salts. It is maintained that these phenomena of absorption-adsorp- 

 tion tend to maintain a practically constant concentration of solution 

 for any given soil. Indeed, it is a.s-serted that it is these properties of 

 the soil which prevent the soil solution from becoming too concentrated 

 either upon withdrawal of moisture or a])])lication of saltf-; to the soil, 



(M) Bui 22, Bureau of Soils, U. S. Dept. of Ags .. 1903. 



