14 



CONTROL SERIES No. 51 



Deficiencies between H and ^ per cent, 12. 



Deficiencies more than % per cent, 14. 



Of the total number of brands analyzed, about 12.9 per cent failed to meet the 

 nitrogen guarantee, 15 per cent faUed to meet the available phosphoric acid 

 guarantee, and 12 per cent failed to meet the potash guarantee. This is 26 less 

 nitrogen, 25 more available phosphoric acid, and 14 less potash shortages than 

 were recorded in 1928. 



Mixing Efficiency Table. 



The above table shows that all but three manufacturers, of the twenty-two 

 listed, had an average overrun in all three plant food elements. Two manu- 

 facturers showed an average shortage in nitrogen, and at least three others showed 

 very small overruns. In available phosphoric acid no average shortages were 

 noted, and only two manufacturers had marginal overruns small enough to call 

 for criticism. One sUght average potash shortage was noted, and one other manu- 

 facturer showed but a small average overrun. Seven of the manufacturers listed 

 should revise their formulas to provide a safe margin of overrun in one or more 

 elements of plant food. 



Explanation of Tables of Analyses. 



Guarantee. This column gives the manufacturer's claim or guarantee for the 

 three elements of plant food, nitrogen, available phosphoric acid and potash, in 

 the order stated. When the nitrogen system is finally adopted by all of the manu- 

 facturers, the guarantee of a fertilizer will be the same as the grade. 



With one exception, wherever the grade of a fertilizer is used as a part of the 

 trade name the order and form express ammonia, available phosphoric acid and 

 potash. The exception noted is the Eastern States Farmers' Exchange. Their 

 grade expression refers to nitrogen, available phosphoric acid and potash, con- 

 forming to the recommendations of both the National Fertilizer Association and 

 the Committee on Definition of Terms and Interpretation of Results on Fertilizers. 



Commercial Shortages. In the table designated "Mixtures showing a com- 

 mercial shortage of $1 or more per ton," the column headed "Approximate com- 



