788 



THE NATIONAL GEOGRAPHIC MAGAZINE 



or conserves his meager store of this 

 most precious element. 



Now how much phosphorus is there? 

 The hthosphere, or outer crust of the 

 globe, holds enormous available supplies 

 of nitrogen, and contains nearly three 

 per cent of potash, well distributed and 

 available as plant food. These suppUes 

 are inexhaustible. 



But it contains only about one-tenth 

 of one per cent of phosphorus. This is 

 phosphorus enough to grow perfect 

 crops, but there is practically no margin 

 for waste. 



Yet the waste is large and constant 

 from every American farm acre, and, 

 under the present practice, the end is in 

 sight for American agriculture — not a 

 thousand years hence, but almost now. 

 In fact it has come to some farm sec- 

 tions. Science realizes it and is preach- 

 ing the danger, but the people, the pro- 

 ducers, cannot see it. Dr. Hopkins, of 

 the Illinois Experiment Station, demon- 

 strates the fact on the so-called inex- 

 haustible black prairie bottom lands of 

 fertile Illinois. What then of the long- 

 cropped lands of New England and the 

 more southern Atlantic Coast States? 

 Let us see what the cold, uncontroverti- 

 ble facts show with relation to the de- 

 generation of the rich and comparatively 

 new farming lands of Illinois, then apply 

 the information to the rest of our farm 

 area, and see how long under present 

 practice we will be able to maintain our 

 agricultural supremacy, and therefore 

 our prosperity as a people. And then, 

 while there is yet time, let us supply the 

 only remedy. 



The average of the different kinds of 

 Illinois soils contains 1,191 pounds of 

 phosphorus per acre for the surface 7 

 inches of dirt. But a 75-bushel crop of 

 corn, for instance, will remove from an 

 acre of soil 17 pounds of phosphorus, 

 and, at this rate of cropping, the total 

 phosphorus content of that soil would be 

 exhausted in 70 years. If the grain is 

 fed on the farm a good proportion of this 

 plant will be returned to the soil. To 

 prove that in actual farm practice the 

 rate of exhaustion is startlingly rapid, a 



series of soil analyses in three States is 

 cited by Dr. Hopkins, and they show 

 that ordinary cropping for 54 years took 

 away 36 per cent of the original phos- 

 phorus content of these soils. 



Now, to replenish soils depleted of thiS' 

 necessary element through cropping, we 

 must draw principally upon the natural 

 supplies of concentrated phosphorus. 

 The greatest source of phosphorus is- 

 phosphate rock, the petrified remains of 

 myriads of antediluvian animals, and the 

 principal deposits of phosphate rock are 

 found in the United States. Again, the 

 greatest of these have been but recently 

 discovered in the public-land States of 

 Wyoming, Utah, and Idaho. This field 

 embraces the largest area of known phos- 

 phate beds in the world. The United 

 States produces more phosphate than all 

 other countries together. To merely off- 

 set the rate of loss above mentioned and 

 maintain the present fertility of all the 

 cropped land in the United States would 

 require the use of over 12,000,000 tons- 

 of phosphate rock annually. 



But people say that there are inex^ 

 haustible supplies of this phosphate in 

 the great deposits of Florida and other 

 States. There are, it is true, large de- 

 posits of this precious mineral, but the 

 supply is far from inexhaustible ; it is- 

 distinctly limited and all too small. 

 Moreover, heavy inroads have been made 

 into it, and the worst of the situation is 

 that one-half of the phosphate mined in 

 America is being exported to enrich the 

 worn-out and competitive lands of for- 

 eign countries. 



"American phosphate for the American 

 farmer" is a good cry; it might well be 

 adopted, not as the warning of the senti- 

 mentalist, but as a grim slogan of self- 

 protection. 



The Geological Survey's last estimate, 

 admittedly conservative, for the total 

 tonnage of the high-grade phosphate de- 

 posits of the United States, was less than 

 150,000,000 tons — a i2-years' supply to 

 offset our present waste. Since then 

 geologic work has developed large de- 

 posits, notably in the public-land States 

 of Wyoming, Utah, and Idaho; so that it 



