248 THE FARMER OF TO-MORROW 



of the soil grains, picking up its modicum of 

 "food" in its flight. So it is the water that 

 comes up from the depths and not the water 

 that goes down from the surface that feeds 

 the plant. 



As this water approaches the surface, evapo- 

 ration becomes more and more rapid. Each 

 molecule, when its time comes, disengages 

 itself from the mineral "food" it has picked 

 up in passage (its modicum of 25 parts per 

 million of potash and 10 parts of phosphorus, 

 etc.) and escapes into the air as vapor, leav- 

 ing behind its parcel of "food" in the upper 

 strata of soil. 



Who will say that an examination of the 

 mineral content of the upper twelve inches of 

 soil gives any true indication of that acre's 

 future store of mineral fertility? 



The content is being constantly augmented 

 by the evaporating capillary water, and, on 

 the other hand, it is being constantly "swept" 

 by the gravitational water, which, in its flight 

 to the lower level, picks up a part, but not 

 all, of the "parcel of food" that had previously 

 been carried to the top. Thus we see that the 

 "number of pounds of potash and phosphoric 

 acid" by which some would measure the life 



