14 



Explanation of Tables of Analyses. 



The column headed "Grade of Fertilizer" gives the minimum guarantee 

 of ammonia, available phosphoric acid and potash. To convert ammonia to 

 nitrogen, multiply by the factor .82. 



Under "Approximate Commercial Valuation per Ton" in the table headed 

 "Mixtures Showing a Commercial Shortage of $1 or more per Ton" is found 

 the sum of the calculated valuation of each element, based on analysis and the 

 trade values found on a preceding page of the bulletin. 



Under "Approximate Commercial Shortage per Ton" in the same table is 

 shown the approximate valuation of the low tests or deficiencies per ton of 

 fertilizer, based on Station analysis. In arriving at these figures the value 

 of overruns was used in all cases to offset shortages. 



Under "Nitrogen," the column headed "Proportion in Water Soluble Form" 

 includes both mineral and water soluble organic nitrogen, all of which is 

 known to be readily available. Under "Quality of Insoluble Organic," good 

 indicates an activity of 55 per cent or better by the alkaline permangana,te 

 method; passed indicates an activity between 50 and 55 per cent; inferior 

 indicates an activity below 50 per cent, all being measured by the same labora- 

 tory method. All samples representing brands containing nitrogen of ques- 

 tionable quality are subjected to tests by the neutral permanganate method, 

 which gives somewhat more favorable results on ammoniates of an organic 

 vegetable origin. All samples are passed without question which show an 

 insoluble nitrogen activity of 80 per cent or better by this method, even though 

 they have shown an activity below 50 per cent by the alkaline method. All 

 samples are passed which show the sum of the mineral, water soluble organic 

 and active water insoluble organic nitrogen equivalent to the minimum guar- 

 antee, even though the activity of the water insoluble organic nitrogen may 

 be below 50 and 80 per cent by the laboratory methods. 



The simplified method of presenting results of analyses of fertilizer mixtures 

 substantially complying with the guarantee, which was adopted in 1921, is 

 followed this season. These tables are self-explanatory. 



Detailed results of analysis of any brand inspected will be furnished to any- 

 one sufficiently interested to make application for the same. 



