Low-grade 



Medium-grade 



Medium high-grade 

 High-grade 



Nitrogen. 



Available 



Phosphoric 



Acid. 



7 



5 .5 

 3.5 



2 



Potash. 



2 



2 



2.5 



1.8 



27S 



4. Representing the amount of Nitrogen in each £°°^ t g 0r 

 grade of fertilizer as 1, we have the following propor- 

 tions of available phosphoric acid and potash in the 

 different grades: 



Composition of Different Grades of Fertilizers. 



Cost of One Pound of Plant-Food in Different 

 Grades of Fertilizers. 



Low- 

 Grade. 



Cost of one pound of Nitrogen 



Lowest 



Highest 



Average 



Cost of one pound of Available 

 Phosphoric Acid. 



Lowest 



Highest 



Average 



* 



Cost of one pound of Potash. 



Lowest 



Highest 



Average 



Cents. 



20 



36.8 

 26.3 



Medium- 

 Grade. 



Cents. 



17.9 

 28.3 

 23 . 2 



Medium 



High- 

 Grade. 



Cents. 



17 

 26 

 21 



5.1 



8.1 

 6.4 



4.4 

 6.9 

 5.4 



High- 

 Grade. 



Cents. 



13.3 

 26.0 

 19.6 



4.25 



7.9 

 6.0 



3.4 

 6.7 

 5.0 



From these data, we readily see the truth of the 

 following statements: 



1. The cost of one pound of plant-food, whether 

 Nitrogen, phosphoric acid or potash, is greatest in 

 low-grade and least in high-grade fertilizers. One 

 purchaser of low-grade goods paid 36.8 cents per pound 

 for Nitrogen, while the highest price paid in high-grade 



