November. 1921] kertii.izek inspection, 1921. 7 



By this method we multiply the per cent of each plant 

 food by the cost per unit and then add these figures to give 

 the total value. 



Employing the pound method we obtain : 



3X20 ^Number of pounds of nitrogen in a ton 60 X $0.32 =$19.20 



8X20^ Number of pounds of phosphoric acid in 



a ton 160 X .0875= 14.00 



2X20= Number of pounds of potash water solu- 

 ble in a ton 40 X .1225= 4.90 



Total commercial value $38.10 



The per cent means the number of pounds in 100 pounds. 

 Since there are twenty hundred pounds in a ton we multiply 

 the per cent by twenty to find the number of pounds of each 

 plant food in a ton. Then by knowing the value of these 

 per pound we can figure the value of each plant food per 

 ton. 



HIGH GRADE VERSUS LOW GRADE FERTILIZERS 



The content of available nitrogen, phosphoric acid 

 (P-jOg) and potash (KoO) determines the value of a 

 commercial fertilizer. Because it costs just as much to mix, 

 bag and to ship a ton of low grade fertilizer as it does for 

 a ton of high grade fertilizer, the cost of the same amount 

 of plant food must be much higher in the low grade fertil- 

 izer. 



The average cost of a 1-8-2 fertilizer the past season was 

 $51.40. The value of the 8 units of PoOg was 8X$i-75 or 

 $14.00. The value of the 2 units of potash was 2X$2.45 or 

 $4.90. The value of the available phosphoric acid and pot- 

 ash then was $14.00 plus $4.90 or $18.90 and the nitrogen 

 cost $51.40 minus $18.90 or $32.50. The average content 

 of nitrogen was 0.94 per cent. One ton then contained 

 .0094X2000 or 18.8 pounds of nitrogen. The cost per 

 pound of nitrogen was $32.50-^18.8 or $1.73. The cost per 

 unit was 2oX$i -73 or $34-6o. On the same basis the aver- 

 age cost per unit of nitrogen in the 4-8-4 fertilizer was 

 $13.00 or less than half as much as in the 1-8-2 fertilizer. 



Table No. i gives the cost of nitrogen in the different 

 brands of complete fertilizers, tankage and nitrate of soda 

 analyzed this past season. 



