OUR GREATEST PLANT FOOD 



787 



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TURNIPS AND CLOVER RESPOND HEAVILY TO PHOSPHATE STIMULATION 



Experiments of Maine Agricultural Station with phosphorus in which raw rock phos- 

 phate applications shows the heaviest yields. 



_ Turnips: Box i, dissolved phosphate; box 2, raw phosphate; box 3, insoluble phosphate 

 of iron ; box 4, no phosphate. 



Clover: Box i, dissolved phosphate; box 2, raw phosphate; box 3, insoluble phosphate of 

 iron; box 4, no phosphate. 



may be reasonable to make a guess of 

 the existence of double this figure, or 

 300,000,000 tons. But every ton of this 

 will be needed on American farms, and 

 it should be our hope that other great 

 deposits may be discovered which will 

 yet again double this tonnage. 



And exportation of this vital element 

 should be stopped. 



The following tables, compiled from 

 the figures of the Geological Survey and 

 the Bureau of Statistics, show the pro- 

 duction and exportation of high-grade 

 phosphate rock : 



