i^^tkoduction: 



Much interest has been manifested in tlie soluble constituents ot the 

 soil for nearly three-fourths of a century, as a result of which many 

 valuable contributions to our knowledge of the subject have been made. 

 Yet a critical examination of the available literature has led to the 

 conclusion that this fundamentally important subject still remains a 

 fertile field for investigation, new and improved methods of attack 

 being especially desirable. Such phases as the rate of solution of soils 

 under different conditions of moisture, temperature, cropping, and sea- 

 son as well as the immediate and residual effect of salts upon solubility 

 should be investigated, and moreover, information concerning the con- 

 centration of the soil solution un<ler field conditions as affected l)y sea- 

 son, ditt'usion, water movements, tillage and cropping is ver^'^ desirable. 

 In view of the situation tlie soil solution is receiving much attenlion by 

 meiidxM-s of tlie Soils Section of the Ttlxperiment Station. Bouyoucos is 

 engaged in researches on the rate and extent of solu)»ility of soils under 

 different conditions and treatments, mainly from the pliysical side, while 

 Spurway is conducting very comprehensive chemical studies of the effect 

 of soluble salts on the solubility of soils. Tn this report are presented 

 data bearing upon the effect of salt movements, moisture, temperature 

 and cropping upon the salt content of several soil classes. 



The writers .arc greatly iiiilebfed to A. G. Weidemann for valiialile assistance rcnilcrcd 

 throughout these investigations. 



