EXPERIMENT STATION BULLETINS. 625 



99.2 and 78.0%, respectively, the increase in the other soil is compara- 

 tively small, amounting in the case of humus loam to only 20%, gray 

 clay 22%, red clay 42%, etc. It is interesting to note that in the red 

 clay the concentration is 20% greater than in the gray clay. Evidently, 

 therefore, the influence of KoSO^ upon the concentration of the soil solu- 

 tion of the various soils is not as great as that of KCl. 



The solution of MgSO^t increased the concentration of the soil solu- 

 tions of some soils quite appreciably, but in others only a very small 

 amount. Thus, in the quartz sand, sandy loam, silt loams, kaolin, and 

 peat the greatest part if not all of the original concentration of this 

 salt solution went to concentrate their soil solutions but in gray clay, 

 humus loam, and red clay, a smaller portion of the original concentra- 

 tion was used for the same purpose. 



The (NH4)2S04 solution increased the concentration of the soil solu- 

 tion of the agricultural soils on the average much less than the MgSO^ 

 but considerably more than the KoSO^. It will be seen that in the quartz 

 sand and kaolin fully the entire concentration of the salt solution was 

 added to their solution, but in the other agricultural soils only about 

 half of the original concentration was imparted to their soil solutions. 



The increase in concentration of the soil solution of the various soils 

 by the Ca(N0o)2 and NaNOj solutions is extremely interesting. It 

 will be noted that in all the soils, with the exception of peat and humus 

 loam, practically the entire concentration of these two salt solutions was 

 added to their soil solutions and the percentage of the Ca(N03)2 is 

 appreciably greater than that of the NaNOg. The failure of both clays 

 to decrease at all the concentration of Ca(N03)o is of especial interest. 



Of all the compounds used, the phosphates increased the concentra- 

 tion of the soil solution of the agricultural soils the least. Indeed, it 

 will be seen that with the exception of quartz sand, peat, and kaolin, 

 the concentration of the solution of the other soils was increased from 

 0.0 to only 8.78% of the original concentration of KsHPO^, CaH^(POJ, 

 and Na, HPO4 solutions. Of the three solutions the last caused the 

 greatest increase in the contentration which is only about 8%. Evi- 

 dently these compounds have very little if any effect upon the concen- 

 tration of the soil solution of most agricultural soils. 



In order to ascertain whether greater concentrations than n / 100 

 of these phosphate compounds would increase the cencentration of the 

 soil solution a normal solution of each was employed. The lowering 

 of the freezing point of n / 1 Na^HPO^ solution, however, could not be 

 determined on account of its saturation point and the consequent pre- 

 cipitation, and, therefore, no calculation could be made to what extent 

 it influenced the concentration of the soil solution, "the following 

 table, therefore, contains onlv the results obtained with n / 1 solution 

 of K,HP04 and CaH,(POj/in red clay. 

 79 



