GS4 STATE BOARD OF AGRICULTURE. 



EXPERIMENTAL WORK. 



Rate and Extent of Solubility of Soils Treated with Single Salt Solu- 

 tions and then Washed until all their Free Solulile Salts were Elimi- 

 nated. Ratio of Soil to Water was 1 to .7 and Mixture ^Maintained at 

 Room Temperature. 



From the logical stand])oint the investigation on the solubility of 

 natural or untreated soils ought to be considered first, but because of 

 the fact that the investigation on the solubility of treated soils presents 

 many more fundamental and general principles and otters a better basis 

 for general understanding and explaining, it is considered first. 



The first study of the solubility of treated soils consisted of measuring 

 the rate and extent of solubility of various soils treated with single salt 

 solutions of tenth normal strength and then washed until all their free 

 soluble salts were eliminated and the washed soils had a freezing ijoint 

 depression almost the same as that of the untreated soils, and very close 

 to that of the distilled water. As a rule the depression was about .010° C 

 or 250 parts per million of solution. In some cases this depression was a 

 little higher. As previously stated the treatment consisted of mixing 

 about 50 grams of soil with 150 c.c. of Solution allowing the mixture to 

 stand about 24 hours, with occasional shaking and then washing the soil 

 by tlie ])rocess of leaching. Some of the washed soil was then placed in 

 the freezing point tube, water being added to it to bring it up to the 

 water content of about 1 of soil to .7 of water, in the case of the heavy 

 types of soils, and to about 1 to .5 in the case of the light type of soils, 

 and the freezing point depression determined immediately, once every 

 day during the first four or five days and quite often thereafter, mean- 

 while the soil being kept at room temperature which average about 20°C. 



There were seven ditferent soils employed in this study, one clay, two 

 clay loams, two silt loams, one sandy loam, and one sand. Each one 

 of these soils was treated with ten ditferent salt solutions, namelv, 

 Ca(N0,)2< NaNO,, KNO:,, KCl, K.,SO„ (NH,V,SO,. MgSO,, KH^Pd, 

 CaHi(P04)2 and ]VaCoH,,0._,. For each treated soil there was always 

 an untreated soil run for a check. Tn all of the salt solutions the strength 

 was tenth normal. 



The results obtained in this study are i^resented in tables 1 to 7 in- 

 clusive. They show the rate and extent of solubility of these treated 

 soils as measured by the freezing point method. For clearness and as 

 an aid to better understanding typical examples of these results are 

 diagranuitically represented in figures 1 to 5 inclusive. In these fig- 

 ures some irregularities are noted. These irregularities are due to slight 

 errors in the determination and to the ditferent changes that are taking 

 place in the soil. Tliey are, however, very insignificant in magnitude 

 and of no consequent importance. 



