6 N. H. AGR. EXPERIMENT STATION [Bulletin 214 



amounts instead of the per cent. The term "unit" means 

 20 pounds per ton of 2,000 pounds, or 1 per cent. One 

 unit means 1 per cent of a ton or 20 pounds. A fertilizer 

 having 4 per cent of nitrogen has four units of nitrogen or 

 80 pounds per ton. 



Prices of Plant Foods. It is impossible to give ac- 

 curate figures for the cost of the different plant foods be- 

 cause the cost of mixing, bagging, freight and the manu- 

 facturers' and dealers' profits vary with the quantity 

 purchased, distance shipped and number of persons through 

 whose hands the material has passed. It is possible, how- 

 ever, to obtain figures which are sufficiently accurate for 

 use in comparing the relative values of fertilizers. 



The average cost of acid phosphate containing 16 per 

 cent of phosphoric acid was $26.20 per ton. One ton con- 

 tained 0.16 times 2,000 pounds or 320 pounds of available 

 phosphoric acid. The cost per pound was $26.20 divided 

 by 320 or approximately 0.082 and one unit of available 

 phosphoric acid cost 20 times 0.082 or approximately $1.64. 



The average cost of muriate of potash containing 50.0 

 per cent of water soluble potash was $43.00 per ton. One 

 ton contained 0.50 times 2,000 pounds or 1,000 pounds of 

 potash. The cost per pound was $43. 00 divided by 1,000 

 or $0,043 and one unit of water soluble potash cost 20 times 

 $0,043 or $0.86. 



The average cost of nitrate of soda containing 15 per 

 cent nitrogen was $63.00 per ton. One ton contained 0.15 

 times 2,000 or 300 pounds of nitrogen. The cost per pound 

 was $63.00 divided by 300 or $0.21 ; this made the cost 

 price per unit 20 times $0.21 or $4.20. The average cost of 

 tankage was $47.40 per ton and it contained an average of 

 5.40 per cent of nitrogen and 7.90 per cent available phos- 

 phoric acid. The value of the 7.90 units of phosphoric acid 

 was 7.90 times $1.64 or $12.96, making the nitrogen cost 

 $47.40 minus $12.96 or $34.44. The cost per unit of nitro- 

 gen was $34.44 divided by 5.40 or $6.38 and the cost per 

 pound of nitrogen was $0,319. If we assume that our com- 



