286 NATURE AND PROPERTIES OF SOILS 



149. Other factors influencing^ the soil solution. — A num- 

 ber of other conditions, which are really phases of season, 

 influence both the concentration and the composition of the 

 soil solution. Among these are temperature, leaching, and 

 the moisture content of the soil. As the soil warms up in the 

 spring, reactions of all kinds are stimulated and an increase 

 in concentration generally results. If considerable rain-water 

 enters the soil, the soil solution is much diluted. It is also 

 changed in composition, due to the equilibrium adjustments 

 that of necessity occur. The following data from Bouyoucos ^ 

 show the influence of change in moisture on the concentra- 

 tion of the soil solution : 



Table LXIV 



concentration of the solution of certain soils at various 

 moisture contents. lowering of the freezing 



point method. 



Soils 



MOIST-QKE 

 % 



CONCBN- 

 TBATION 



P. P. M. 



Moisture 

 % 



Concen- 

 tration 



p. p. M. 



Sand 



Sandy loam. . . . 

 Loam 



2.60 



8.30 



11.18 



17.40 



18.80 



3,939 

 13,639 

 13,780 

 20,153 

 28,940 



21.98 

 21.53 

 20.97 

 34.76 

 36.50 



303 

 606 



848 



Silt loam 



Clay 



1061 

 1030 







If the soil is moistened beyond its water-holding capacity, 

 it is obvious that drainage losses will occur, which will deplete 

 the soil of valuable constituents. Increase of moisture, there- 

 fore, may modify the soil solution temporarily or permanently, 

 according to conditions. 



Tillage and the addition of various materials also have a 



^Bouyoueos, Gr. J.^ The Freezing Point Mefhod as a New Means of 

 Measuring the Concentratio7i of the Soil Solution Directly in the Soil; 

 Mich, Agr. Exp. Sta., Tech. Bui. 24, 1915. 



