. EXPERIMENT STATION BULLETINS. 



647 



TABLE 12— EFFECT OF PERCOLATION OF WATER UPON THE SALT CONTENT OF SOIL 



Silt Loam. 



111 case of the medium sand 3 inches of water removed practically all 

 of the soluble material to the nine-inch depth and samples taken after 

 twelve inches of water had been added showed freezing depressions only 

 slightly higher than distilled water. 



EFFECT OP CROPS ON SALT MOVEMENTS. 



Growing crops alTect salt movement in soils. A number of samples 

 were taken from soils occupied by spring grains, grasses, and meadows 

 and adjacent areas upon which plant growth was prevented. In taking 

 samples the surface was removed to a depth of one-fourth inch. At the 

 time of sampling the ijiiiit'.ill liad been inappreciable for thirty days. 



TABLE i;!.— 10FFK( r OF CHOPS UPON SOLUBLE SALTS PRESENT IN SOILS. 



In all except the sands the freezing point lowerings of the surface 

 soils showed an accumulation of salts where the land was bare. 



It seems that the difference between the cropped and uncropped soil 

 in this respect is due to differences in water content, water movement,; 

 temperature, and to the removal of soluble constituents by the growing 

 plants. The sandy soils studied, rapidly mulch themselves and conse- 

 quently deposition of salts at the surface is prevented. If samples had 



