Food for SUPERPHOSPHATE. In natural phosphates the phos- 



phoric acid is insoluble in water and not available to plants, 

 except in the form of a very fine powder. Superphosphate is 

 prepared from these by grinding and treating with sulphuric 

 .acid, which makes the phosphoric acid more available. Super- 

 phosphates are sometimes called acid-phosphates. 



POTASH, as a constituent of fertilizers, exists in a num- 

 ber of forms, but chiefly as sulphate and muriate. The chief 

 sources of potash are the potash salts, muriate of potash, sul- 

 phate of potash. Canada wood ashes and cotton-hull ashes 

 are also sources of potash, as is also Nitrate of Potash. 



Ammoniates. Nitrogenous Fertilizers. 



Per Cent. 



Nitrogen. 



Nitrate of Soda 15-65 



Dried blood 13.00 



Tankage 12.00 



Dry fish scrap 9.00 



Cotton-seed meal 7.50 



Barnyard manure 0.05 



Phosphates. 



Per Cent. Lbs. Phosphoric 

 Phosphoric Acid. Acid Per Ton. 



Superphosphate 14 280 



Ground bone 22 440 



Bone tankage 12 240 



Barnyard manure 0.32 6.40 



Potashes. 



Per Cent Actual Lbs. Potash. 



Potash. Per Ton. 



Nitrate of Soda i to 3 20 to 60 



Muriate of potash 50 1,000 



Sulphate of potash 52 1,040 



Canada wood ashes 6 120 



Cotton-seed hull ashes 25 400 



Waste from gunpowder works 18 360 



Corn cob ashes 23 460 



Maryland marls 1.25 25 



Castor pomace 1.5 30 



Tobacco stems 6.5 130 



Barnyard manure 0.43 S.6 



