20 



Rogers & Hubbard Co. Rogers' High Grade Soluble Corn and 

 Onion Manure, Nos. 187, 318, 875. Nitrogen found 2.58%, guaran- 

 teed 2.50%; available phosphoric acid found 8.18%, guaranteed 

 10.00%. 



Rogers' High Grade Soluble Tobacco Manure, Nos. 186, 317, 

 322. Nitrogen found 5.19%, guaranteed 5.00%; available phos- 

 phoric acid found 7.78%, guaranteed 10.00%. The manufacturer 

 claims that dissolved bone has been used to furnish a considerable 

 part of the available phosphoric acid, and investigation seems to 

 show that the low phosphoric acid availability may be due to the use 

 of an insufficient amount of sulfuric acid to completely acidulate the 

 bone. The total phosphoric acid was found well up to the guarantee 

 in both cases. 



Sanderson Fertilizer & Cheynical Co. Sanderson's Double 

 Strength Ammonia Mixture, Nos. 211, 369. Nitrogen found 5.61%, 

 guaranteed 6.58%; available phosphoric acid found 9.16%., guaran- 

 teed 8.00%. 



Whitman & Pratt Rendering Co. 3-10 Brand, Nos. 563,678. 

 Nitrogen found 2.26%, guaranteed 2.47%; available phosphoric 

 acid found 9.58%, guaranteed 10.00%. 



QUALITY OF PLANT FOOD IN MIXED FERTILIZERS. 



Nitrogen in Complete Fertilizers. A study of the nitrogen used in 

 the formulas classed as complete fertilizers for 1917, shows that the 

 average total nitrogen found was 3.09 per cent, nitrates and ammoni- 

 ates 1.62 per cent, and organic nitrogen 1.47 per cent. In other words, 

 52.4 per cent of the total nitrogen was in form of nitrates and ammoni- 

 ates, and 47.6 per cent in organic form. The nitrogen derived from 

 mineral sources, — that is, from nitrates and ammoniates, — is readily 

 soluble in water and wholly available. The quality of the organic 

 nitrogen used in these mixtures is indicated by the following averages : 

 water soluble organic .41 per cent, water insoluble organic 1.06 per 

 cent, of which .59 per cent was found active and .47 per cent inactive 

 by the laboratory methods. The average total nitrogen in the com- 

 plete fertilizers had a percentage activity of 84.79 per cent, the total 

 organic nitrogen 68.04 per cent, and the water insoluble organic 

 nitrogen 55.66 per cent. 



Nitrogen in Ammoniated Superphosphates. The following data 

 show the quality of nitrogen used in these mixtures: average total 

 nitrogen found 3.48 per cent, nitrogen in form of nitrates and am- 



