300 Bureau of Farmers' Institutes. 



amounts of plant food. Moreover, lie should insist that the guar- 

 antee be in the following terms: 



Nitrogen for all forms of nitrogen. An added statement as to 

 whether the nitrogen comes from nitrate, ammonia compounds, 

 dried blood, cotton seed meal, etc., is desirable. 



Available Phosphoric Acid or preferably water soluble and re- 

 verted phosphoric acid separately for all forms of phosphoric acid. 



Potash actual for all forms of potash, though it may be desirable 

 to have stated in addition whether the potash is present as sul- 

 phate free from chloride or as muriate. 



In examining a guarantee, pay attention only to the nitrogen, 

 a callable phosphoric acid and actual potash, and require the guar- 

 antee to be in these terms before purchasing. 



2. Total Constituents of Fertilizers. 



If we add together the figures representing the different con- 

 stituents of a fertilizer appearing in a chemical analysis (the 

 nitrogen, the total phosphoric acid, and the potash), we shall find, 

 as a rule, that the sum amounts to only 20 or -SO per cent, or pounds 

 per hundred. The question often arises, " Why does the sum of 

 the constituents in the analysis of a fertilizer amount to only 20 

 or 30 per cent., and what is the remaining portion, amounting to 

 70 or 80 per cent, made up of ? " A few illustrations will, per- 

 haps, suffice to make the matter clear. 



Higii-Grade Fertilizers. — Taking a fairly high-grade fer- 

 tilizer, we find by analysis that it contains : 



Per cent. 



Nitrogen 4 



Available phosphoric acid 8 



Insoluble phosphoric acid 2 



Potash • 10 



If the nitrogen comes from dried blood or meat, it will take 

 about j0 pounds of such material to furnish one pound of nitrogen. 

 Since there are four per cent, of nitrogen, or four pounds of nitro- 

 gen in 100 pounds of fertilizer, it will take 40 pounds of dried 

 blood to furnish this amount of nitrogen. The amount of bone 

 and sulphuric acid necessary to make a phosphate containing eight 



