71S • STATE BOARD OF AGRICULTURE. 



.054" in Michigan clay loam (No. 8), to .004° in Michigan brown silt loam 

 (No. 12) to .070"(J in Michigan brown silt loam. 



The influence of the high temperature on the solubility is very differ- 

 ent in the various soils. In some soils it is very marked and in others 

 hardly perceptible. In all of the clays, in all the sands and in a few 

 sandy loams the influence is rather small, the difference in depression 

 being only about .010°, while in practically all the clay loams, silt loams, 

 and a few sandy loams the influence is rather large, amounting to a dif- 

 ference of depression of over .025°C in some cases. While many of the 

 soils, in which the solubility product was greatly increased by the high 

 temperature, contained a high organic matter content, there are few 

 soils which contained only a very small amount of organic matter and 

 yet their solubility product was also greatly increased. Thus, fine sandy 

 loam (No. 31), Hanford fine sandy loam contained only a small amount 

 of organic matter and yet the aiuount of material that went "into solution 

 was greatly increased. Hence, it is not only organic matter which is 

 materially affected by the high temperatnre but also some other soil con- 

 stituents. Undoubtedly, however, the organic matter was affected the 

 most. 



It is interesting to note the Cecil clay even at the temperature 

 of 53 °C gave no more material to solution than at the room temperature 

 and that it attained equilibrium rather quickly. The amount of ma- 

 terial that this soil allowed to go into solution at this high temperature 

 is exceedingly small, amounting only to about 250 parts per million. 



Rate and Extent of Solubility of Natural or Untreated Soils Which 

 Were Previously Washed and Ratio of Soil to Water was About 1 to .7 

 and Mixture Maintained Below Freezing Temperature. 



Having presented the investigation on the effect of high temperature 

 on the rate and extent of solubility of soils, the influence of low tem- 

 perature on these same factors are now in order. 



This study was conducted by putting washed soils in the freezing point 

 tubes with a water content of 1 of soil to .7 of water, determining the 

 freezing point depression, then stoppering the tubes, placing them out- 

 doors in the cold weather and tlicn at the end of 30 days the soils were 

 thawed and their free.^ing point depression again determined. The soils 

 were placed outdoors during the month of January when the tempera- 

 ture for the whole month was always below freezing and most of the time 

 at or below zero Fahrenheit. At no time did the temperature rise suffici- 

 ently to thaw the soils. The soils, therefore, remained frozen during the 

 whole period. The soils used were the same as in the preceding study 

 The results obtained are shown in table 25. 



