New York Agricultural Experiment Station. 667 



obtained at $4 to $5 a ton, furnishing calcium at about the same 

 price (0.3 cent a pound). 



In this connection, it is in place to mention that one sample of cal- 

 cium sulphate (gypsum or land-plaster) was found containing 26.75 

 per ct. of calcium, and selling at $10 a ton. In this case each pound of 

 calcium costs 1.9 cents. It may be added that calcium in this form 

 has no value in neutralizing soil acidity. 



composition and cost of mixtures containing lime, phosphoric 



acid and potash compounds. 



Quite recently mixtures have come into the market which contain 

 calcium carbonate in the form of ground limestone or marl together 

 with muriate or sulphate of potash and ground rock phosphate or 

 acid phosphate. Some of the mixtures are intended by the makers 

 to imitate wood-ashes in composition. 



Table XVII. — Amount and Cost of Calcium, Phosphoric Acid and 

 Potash in Special Mixtures. 



Pounds of phosphoric acid in 100 pounds 



Pounds of potash in 100 pounds 



Pounds of calcium in 100 pounds 



Selling price of one ton 



Commercial valuation of one ton 



Cost of one pound of phosphoric acid 



Cost of one pound of potash 



Cost of one pound of calcium 



Average. 



4.48 



4.97 



32 50 



$17.12 



9.01 



7.6 cents 



7.6 cents 



0.95 cent 



From the standpoint of economy in the purchase of plant-food, 

 these mixtures do not appear to offer any advantage. Plant-food 

 can be purchased much more cheaply in the usual forms found in the 

 market. The cost of phosphoric acid and potash in these mixtures 

 averages considerably higher even than in low-grade complete 

 fertilizers. 



SUMMARY OF RESULTS RELATING TO COST OF PLANT-FOODS IN 



FERTILIZERS. 



In Table XVIII we bring together in condensed form the re- 

 sults that have been presented in the preceding pages, making them 

 more available for comparison. 



