New York Agricultural Experiment Station. 659 



composition of bone and potash mixtures and cost of 



plant-food. 



A few mixtures are found in the market containing bone-meal and 

 potash salts. Several samples were analyzed. 



Table V. — Amount and Cost of Nitrogen, Phosphoric Acid and Potash in 



Bone and Potash Mixtures. 



The cost of plant-food constituents is high in comparison with their 

 cost in complete fertilizers of medium high grade. The cost of nitro- 

 gen and phosphoric acid is also high in comparison with their cost in 

 bone-meal and in tankage. The variation in selling price is much 

 greater than is justified by the variation in the amount of plant-food 

 contained in the different samples. In connection with the cost of 

 phosphoric acid in comparison with the available phosphoric acid of 

 ordinary complete fertilizers, it must be kept in mind that the phos- 

 phoric acid of bone is less quickly available than in case of the phos- 

 phoric acid supplied by acid phosphate. 



AMOUNT AND COST OF PLANT-FOOD IN ACID PHOSPHATES. 



Most of the soluble phosphoric acid in the market is acid phosphate 

 made from phosphate rock by treatment with sulphuric acid. Until 

 quite recently it was the prevailing custom to give misleading names 

 to this material such as " dissolved bone," " soluble bone," etc. It is 

 therefore interesting to observe that of the 57 samples of acid phos- 

 phate given in Bulletin No. 390, not a single one is given a brand name 

 containing the word "bone." In only two cases are the brand names 

 such as to give no indication of the composition of the material. The 

 results of our work are given in the following tabulated form : 



