300 University of California PuhJications in Agricultural Sciences [Vol. 1 



Na2S04 and NaoCOg was also decidedly reduced, as shown by 

 the respective percolation rates of .31 cc. and .37 cc. per hour. In 

 significant contrast thereto, the maintenance of a comparatively 

 uniform salt content in the soil column, 'produced by substituting 

 solutions of the salts for the distilled water as in the case of 

 Nos. 12, 13, and 14, r^reates a favorable condition for percolation, 

 except in No. 14, which received NaoCOa- In this case percola- 

 tion averaged a rate of 1.07 cc. per hour, which was less than the 

 control, but three times that of the soil receiving NaoCOg and 

 distilled water. It is of interest to note the immediate depression 

 in the rate of percolation when distilled water is used instead of 

 the salt solutions of Nos. 12. 13, and 14. Eventually the rate of 

 percolation from these soils under applications of distilled water 

 approached that of the soils originally treated with salts and 

 which in addition had received only distilled water throughout 

 the experiment. 



Another percolation experiment, arranged somewhat similarly 

 to the preceding, demonstrated that the relative position of the 

 salt in the soil column, or the manner of adding it, had little or 

 no influence on the depressing effect noted on percolation. It was 

 further observed that a soil, the percolation rate of which had 

 been diminished through the agency of NaCl and 11,0 applica- 

 tions, failed to recover its original rate of percolation even when 

 a solution of that salt was applied for the second time. 



The general trend of the results thus far secured is in accord 

 with Beeson's observations,^ in which he recorded a delayed 

 absorption of water by soils containing sodium salts as well as 

 a pronounced retarding of percolation through soils to which 

 various salts had been added. Like many other uavestigators 

 who have observed similar effects resulting from salt treatments, 

 Beeson failed to recognize any connection between the physical 

 condition of the soil and the removal of the salt, but attributed 

 the peculiar changes observed in the soil to surface-tension 

 phenomena, or other alterations in the physical properties of the 

 liquid phase, or, as some investigators are inclined to believe, 

 to a shifting of the soil particles to new positions through the 

 influence of the added salt. Undoubtedly a movement of soil 



s Journ. Am. Chem. Soc, vol. 29, p. 620, 1897. 



