16 The Phosphates of America. 



Wheat 40,000,000 acres 



Maize 75, 000, 000 



Oats 23,000,000 " 



Barley 2,500,000 " 



Rye 1,800,000 " 



Buckwheat 900,000 " 



Total 143,200,000 " 



The quantity of phosphoric acid per acre is therefore, for the 

 whole cereal crop : 



2,714,585,473 -4- 143,200,000 = 19.0 pounds. 



For the hay crop a similar estimate may be made of the quan- 

 tities of plant food removed. 



The mean percentage of ash in the grasses of the United States 

 is 7.97 ; for timothy it is 5.88 ; for clover it is 6.83. The mean 

 content of ash may consequently be taken at 6.89 per cent. The 

 total weight of hay produced, multiplied by this number, gives 

 6,201,000,000 pounds as the total weight of ash in the hay crop of 

 the United States. 



For the ash of timothy the percentage of phosphoric acid is 

 8.42 ; for red clover, 6.74. The mean percentage of phosphoric 

 acid in the ash of timothy and clover is, therefore, 7.56. 



The total weight of phosphoric acid in the hay crop there- 

 fore is 



6,201,000,000 X 7 ' 56 = 468,795,600 pounds. 

 100 



The number of acres harvested in the United States is about 

 37,500,000, and the quantity of phosphoric acid removed per acre 

 is consequently 



468,795,600 -4- 37,500,000 = 12.5 pounds. 



