256 THE FARMER OF TO-MORROW 



fact has been the cause of some bitter re- 

 criminations. 



In attacking the hypothesis of "immutable 

 assets," the first point considered vulnerable 

 and dangerous to teach is the statement 

 that potash and phosphorus are always avail- 

 able in sufficient ratio to feed plants. 



Professor Edward J. Russell (Science 

 Progress, Vol. VI.), of the Rothamsted Sta- 

 tion, examines the theory of the Bureau of 

 Soils in detail, and rejects the assertion of free 

 solubility of the soil minerals as unfounded. 

 He accepts the German theory that soil grains 

 are rendered insoluble by a coating of silicates, 

 which acts in the same way as a hollow glass 

 ball filled with common salt. The glass would 

 prevent the water from coming in contact with 

 the salt and therefore withholds it from 

 solution. 



Doctor Cameron and James M. Bell, in 

 their experiments as to the solubility of min- 

 erals (Bulletin 30, Bureau of Soils), admit 

 that they reached a point in some of their ex- 

 periments where further potash could not be 

 removed from soils by leaching without re- 

 grinding the soil grains, and state that "this 

 gradual cessation of the yield of potash has 



