386 



Journal of Agricultural Research 



Vol. XII, No. 6 



It will be noted that there are no marked or consistent changes in the 

 freezing-point depressions as a result of the air-drying. In samples 5A 

 and 5B water extractions (i to 5) were made with the result that only 

 negligible increases occurred in the quantity of any of the constituents, 

 with the exception of the organic matter which was made somewhat 

 more soluble. It may be suggested that a further increase in the con- 

 centration of the soil solution might subsequently be caused through 

 stimulation of bacterial activity caused by the additional organic nutrj- 

 ment made available. In this case the solubility of various elements 

 would be increased indirectly by drying, but there is no evidence that 

 nutrient elements become more soluble by the simple process of drying 

 at ordinary temperatures. 



EXPERIMENTS WITH LEACHED SOILS 



All of the foregoing work has consistently indicated that a given soil 

 may yield very dififerent soil solutions under different conditions. In 

 order to establish the lower limits, it was decided to leach several soils 

 with distilled water and then determine the depression of the freezing 

 point. These were determined immediately after leaching and at inter- 

 vals over several months, during which time the soils were kept at 

 laboratory temperature in closed jars. Table VI shows the results ob- 

 tained. 



Table VI. — Effect of leaching on freezing-point depressions 



Soil No. 



2B. 



loB. 



8C. 



5C. 



Treatment. 



fSoo gtn. leached with 2 liters of 

 \ water. 



.do. 



1,000 gm. leached with 10 liters 

 of water. 



.do. 



Freezing-point depression. 



Before leaching. 



Deter- 

 mined. 



O. 117 



306 



207 



. 060 



Water. 



Per cent. 



17. 2 



14-3 



21.5 



After leaching. 



Date. 



Nov. 3 



Nov. 8 



Dec. 5 



Feb. 26 



May 2 



Nov. 3 



Nov. 8 



<!Dec. 5 



Feb. 26 



May 2 



Jan. 9 



Feb. 6 



iFeb. 26 



[May 2 



fFeb. 6 



{Feb. 26 



[May 2 



Deter- 

 mined. 



°C. 



0.034 



. 021 



•033 

 •034 

 .030 

 . 027 

 . 020 

 .032 

 . 040 

 .051 

 . 004 

 . 006 

 . 012 

 •043 

 • 013 

 .049 

 . 064 



Per cent. 



20. 4 



17. 2 



17. 6 



22. 4 



