THE FARMER OF TO-MORROW 



Bureau of Soils, p. 11) at the rate of 150,000 

 pounds per square inch, or approximately fif- 

 teen times the muzzle pressure of a 12-inch 

 gun. It is in this film surrounding the soil 

 grains (which, we have seen, actually exist at 

 less than 1-125 billionths of an inch in diam- 

 eter) that the plant food solutions are held 

 in great concentration due to pressure. It 

 is this property of soils that holds the excess 

 "plant food" and liberates it to the circulating 

 soil waters at a definite rate. Thus the soil 

 conserves its own resources by a method al- 

 most beyond the conception of man. 



