EXPERIMENT STATION BULLETINS. 619 



maguitude of the increase is by far greater iu those soils in Avhich the 

 organic matter is very high or predominates, than in the mineral soils. 

 Apparently steam heat causes a greater amount of material to go into 

 solution in the former than in the latter classes of soil. 



Besides employing the freezing point method to determine the con- 

 centration of the soil solution in the soil at various moisture contents, 

 it can also be used, of course, to measure the salt content of alkali 

 Boils. Through the kindness of Dr. F. S. Harris of the Utah Agricul- 

 tural College we were able to secure soil samples of alkali, irrigated 

 and non-irrigated soils. All these soils could be classed as heavy sandy 

 loams. The lowering of the freezing point obtained from these soils 

 is shown in the following table. 



It will be readily seen that the depression and hence the concentra- 

 tion of salts in solution are very great in the alkali soil, even at such 

 high moisture content, almost at the saturation point; at a Ioav mois- 

 ture content the depression was so great that it could not be read on 

 the scale of the therniometer. The depression of the non-irrigated soil 

 is greater than that of the irrigated even though the moisture content 

 of the latter is greater than that of the former. The magnitude of the 

 depression in both cases, however, is small due to the high water content 

 present. 



In conclusion, then, it must be stated that if it is to be accepted that 

 the loweriug of the freezing point of soils at the different moisture 

 contents represents actual concentration of solution, then many ex- 

 tremely important and far-reaching consequences follow. (1). The 

 soil solution is not under all conditions dilute as is generally believed. 

 It is dilute only at the high moisture content but at a low moisture 

 content it is tremendously concentrated and its concentration can be 

 increased by the application of soluble salts. (2). The concentration 

 of the soil solution does not remain constant but varies tremendously 

 with the moisture content and the amount of soluble salts applied. 

 (3). The solution of normal soils in humid regions may never reach a 

 saturation point, at least with most salts. (4). The magniture of concen- 

 tration of solution is not the same for all soils, but varies greatly with 

 the different soils. (5). The absorbtive power of the soil does not 

 seem to influence at all the concentration of the solution; those soils 

 knoAvn to posses.s fhe highest absorbtive power generally contain a very 

 high concentration of solution and those that have a low absorbtive 

 power possess a low concentration of solution. Hence, the two pre- 

 vailing theories regarding the concentration of the soil solution are 

 diametrically opposed by the results of this investigation. 



Furthermox'e, the acceptance that the lowering of the fi-eezing point 



