While the word fertilizer does not appear in all the above titles, no publica- 

 tion is included which does not discuss the use of fertilizer. 



CONFORMITY TO GUARANTEE 



The chemical analyses were made by the methods of the Association of 

 Official Agricultural Chemists. 



Number of brands analyzed 91 



Equalling or exceeding all guarantees 47 



Deficient in nitrogen only 14 



Deficient in available phosphoric acid only 9 



Deficient in potash only 10 



Deficient in nitrogen and phosphoric acid 5 



Deficient in nitrogen and potash 5 



Deficient in phosphoric acid and potash 1 



Six brands were guaranteed to contain magnesium oxide. None failed to meet 

 the guarantee. In general, the overrun in plant food guarantees exceeds the 

 deficiencies when all brands of a manufacturer are included. 



Fertilizers are largely mixtures of highly purified chemicals. Segregation 

 of these materials in the bag may be expected. To obtain a truly representative 

 sample of a fertilizer mixture requires careful work. The chemist can accurately 

 determine the nitrogen, phosphoric acid and potash content of the sample sent 

 to the laboratory. If this sample does not correctly represent the larger lot, 

 the analytical work is of no use. The obligation of the fertilizer control pro- 

 gram is to see that the manufacturer is supplying the guaranteed amount of 

 plant food to the consumer. For this reason the sample must be drawn and 

 analyzed very carefully so that injustice will not be done to either the con- 

 sumer or manufacturer. 



In the tabulation of the analyses in the following pages deficiencies of one- 

 half per cent or more are shown in red type. The names of the manufacturers 

 are arranged alphabetically. The brand names are listed alphabetically, or 

 numerically by formula, under the manufacturer. 



