MOVEMENTS OF SALTS IN SOILS. 91 



days; but l.el< \v the surface inch it bmi acquired a ncjirl-- uni- 

 form distribution to the two lower layers, which showed so little 

 as to appear like incorrect determinations or else large absorp- 

 tions. The strength of the solution added was such that 20 

 per cent, of it in the soil would carry to the soil about 32 parts 

 per million of its dry weight. The soil itself gave over to dis- 

 tilled water, before treatment, 55 parts per million, which added 

 to 32 parts gives 87 parts, and this is below the amount found 

 in nearly all except the upper and lower layers. In the column 

 to which distilled water was added the SO 4 in the bottom lay- 

 ers also fell but not so low as the results found in the 20 day 

 cylinder. 



In the Selma Silt Loam, too, above the 22-24 inch layer, 

 nearly constant amounts were recovered from the successive lay- 

 ers up to the 1-2 inch level, but these amounts exceed the sum 

 of that recovered from the untreated soil and that which would 

 be carried to the soil with the solution used, this ranging, ac- 

 cording to the per cent, of water in the soil, from 130 to 150 

 parts per million of the dry soil. Indeed the solution, on its 

 way upward through the soil, dissolved other sulphates present 

 and to such an extent as that the amount found, at the end of 

 20 days of capillary movement, was equivalent to 1,362 Ibs. 

 per acre for the 24 inches of soil under treatment. If refer- 

 ence is made to the data of the 50 day cylinder, it will be seen 

 that a change must have occurred before its close, whereby the 

 sulphates which were at first liberated became again absorbed 

 or were precipitated, from which it appears that soil solutions 

 may undergo frequent and often radical changes as they reverse 

 their direction of movement with, changes of the water-content 

 in the soil, and it may be reasonably expected that such changes 

 influence the growth of crops, sometimes favorably and some- 

 times adversely. 



In Fig. 5, p. 1)2, the changes, in, the distribution of sulphates, 

 which occurred in the Miami Loam, are graphically repre- 

 sented, and from this it appears that, during the advance of the 

 solution through the Miami Loam, it had the effect of leaving 

 less SO 4 , in form to be recovered, at the end of 20 days than 

 there was present in the soil to begin with in all layers, except 



