16 



The above table shows that the increased cost of a pound of nitrogen from nitrates 

 and ammoniates has been about 7 cents; of organic nitrogen 10.8 cents; of available 

 phosphoric acid 1.9 cents; and of potash 1.4 cents, when derived from brands which 

 furnish less than 14 per cent of available plant food. These increases would be some- 

 what more if freights, cartage and handling were taken into consideration. The above 

 increases assume considerable proportions when considered from the standpoint of a 

 common fertiUzer application per acre. In case of a 4-8-6 brand, which is not infre- 

 quently used at the rate of one ton per acre for garden vegetables and potatoes, the 

 66 pounds of nitrogen, 160 pounds of available phosphoric acid and 120 pounds of 

 potash would actually cost over Sll more per acre if bought in form of the average 

 low-analysis mixtures. 



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 "Mix- 

 tures 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 aU 

 cases to offset shortages. 



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

 cludes nitrogen as nitrates and ammoniates and water soluble organic nitrogen, aU 

 of which are kno^vn to be readily available. Under "Quality of Organic", good indi- 

 cates an activity of the water insoluble nitrogen of 55 per cent or better by the alka- 

 line permanganate 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 labo- 

 ratory method. All samples representing brands containing nitrogen of questionable 

 quality are subjected to tests by the neutral permanganate method, which gives some- 

 what more favorable results on ammoniates of an organic vegetable origin. AU samples 

 are passed without question which show an activity of 80 per cent or better by this 

 method, even though they have showTi 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. Serious deficiencies are emphasized 

 by boldface type. 



The smiplified method of presenting results of analyses of fertilizer mixtures sub- 

 stantially 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. 



