SOLUBLE SALT CONTENT OF SOILS AND SOME FACTORS AF- 

 FECTING IT. 



Technical Bulletin No. 43 



BY M. M. M^COOL AND C. E. MILLAR. 



SALT MOVEMENT. 



Salt movements affect the concentration and composition of different 

 layers of soil. By means of the freezing point method (1) it was shown 

 that the translocation of added salts in soils is appreciable even in the 

 absence of moisture movements, the water content and the mass of salt 

 present being very important considerations. Moreover, data were pre- 

 sented which show that an application of a given salt at one point in 

 the soil may release another which in turn may be translocated to an 

 adjacent layer of soil (2). 



In these studies 300 grams of medium sand and silt loam respectively 

 were treated with 1% sodium chloride and placed in the bottom of 3 

 gallon jars and the filling completed with untreated moist soils. One 

 set was unsealed in order to permit loss of water by evaporation. The 

 depression of the freezing point of the different laj'^ers of soil and the 

 amount of certain bases found in the water extracts of the same are 

 given in table 1. 



TABLE 1. — CHANGES IN THE COMPOSITION OP THE SOIL SOLUTION INDUCED BY 

 THE ADDITION OF ONE PER CENT SODIUM CHLORIDE TO A MEDIUM SAND AND 

 A SILT LOAM. DURATION 1.5 DAYS. 



CLOSED CONTAINERS. DURATION 25 DAYS. 



(1) Bouyoucos, G. J. and McCool, M. M. 1915. The Freezing Point Method as a New Means 

 cf Measuring the Concentration of the Soil Solution Directly in the Soil. Mich'. Agr. Bxpt. 

 Sta. Tech. BuL 24, 44 pp. 



(2) McCool, M. M. and Wheeting, L. C. 1917. Movement of Soluble Salts Through Soils. 

 In .Tournal of Agricultural Research, Vol. XI. No. 11, p. .531-547. 



