714 STATE BOARD OF AGRICULTURE. 



A close and tlioroiigli examiiialioii of tlie above data reveals many in- 

 teresting and important facts. First of all it is shown that there is 

 wide difference both in the rate and extent of solubility in the various 

 soils. In many soils the rate of solubility is slow and gradual and the 

 process continues a long time, but usually for about 30 or 40 days and 

 the extent of solubility is rather appreciable. Thus, in soils Nos. 9, 10, 

 11, 12, 14, 16, etc., the depression rises slowly and gradually from about 

 .007 °C to about .040 °C in 30 days and to about .050 °C in 99 days. In 

 many other soils the rate of solubility is also slow and gradual and the 

 process continnes for a long time, but the extent is not large. Thus, in 

 soils Nos. 1, 2, 3, 5, 6, 7, 8, 21, etc., the freezing point depression rises 

 from about .000 °C to about .020 °C at the end of 30 days, to about .025 °C 

 at the end of 99 days. In still other soils the rate is not only very slow, 

 but the extent is also extremely small. Thus, in soils No. 4, 19, 22, 26, 

 32, etc., the freezing point low(M'iug rises from about .006° C to only 

 .010°C at the end of'99 days. 



The data fail to show any close and consistent correlation between the 

 class of soil and the solubility factor or tlie total amount of material 

 going into solution. Beginning first with the clays it is at once seen 

 that the final depression varies from .010°C in the case of Georgia Cecil 

 clay, to .023° in Wisconsin Superior clay, to .026° in Texas Houston clay. 



Considering next the clay loam it is readily observed that the lowering 

 of the freezing point varies from .023° in the case of California Ramona 

 clay loam (No. 7) to .032°C in Michigan clay loam (No. 8) to .052°C in 

 Michigan clay loam (No. 9). 



In the case of the silt loams the variation in the depression ranges 

 from .013° in the case of Memphis silt loam (No. 19) to .040° in Penn- 

 sylvania silt loam (No. 17) to .050° in Michigan brown silt loam (No. 11). 



Even in the saiid}^ loams the variation is quite striking. Thus, Ala- 

 bama Dekalb sandy loam (No. 30) gives a depression of only .010 while 

 Michigan fine sandy loam gives a depression of .037° C or a difference of 

 .025 °C. 



The variation in the sands is very negligible. The depression of the 

 freezing point of sands used is about .010 °C for all of them. 



It is conclusively evident, therefore, that there is no relationship be- 

 tween the solubility factor or amount of material going into solution 

 and the class of soil. 



It is also evident that soils with the greatest surface or fineness of 

 particles do not have the greatest solubility ])roduct. Of all the soils 

 employed the clays must possess the greatest surface, witli the possible 

 exception of peat, yet the solubility product of these soils is suialler 

 than that of clay loams and silt loams, and in some cases it is ouly 

 as great as that of sands. 



It may appear that soils with large amounts of organic matter content 

 yield the largest amount of material in solution. While this ma}' be 

 true in many soils yet there are many soils which contain a large amount 

 of organic matter which did not give a high solubility product. Soils 

 Nos. 3, 20, 15, 35, etc., may be cited as examples, while soils Nos. 14, 

 16, 31, etc., contained very little organic matter and yet they yielded a 

 high solubility product. It appears that if organic matter influences 

 the solubility it is not so much its quantity as it is its quality, as many 



