CONFORMITY TO GUARANTEE 



The chemical analyses reported in this bulletin were made by the methods 



adopted by the Association of Official Agricultural Chemists. The following list 

 shows the number of deficiencies found. 



Number of samples analyzed 125 



Equalling or exceeding all guarantees 66 



Deficient in nitrogen only 23 



Deficient in available phosphoric acid only 18 



Deficient in potash only 6 



Deficient in nitrogen and phosphoric acid 5 



Deficient in nitrogen and potash 3 



Deficient in phosphoric acid and potash 2 



Deficient in nitrogen, phosphoric acid or potash 2 



Twenty-one brands were guaranteed to contain magnesium oxide. All 

 equalled or exceeded the guarantee. 



Fertilizers are largely mixtures of chemicals. Segregation of these materials 

 in the bag is difficult to prevent. Modern methods of fei'tilizer manufacture are 

 doing much to process the fertilizer in such a way that segregation will be 

 avoided. The solution of this problem is difficult. 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 laboratoiy. If this sample does not correctly represent the larger lot, the 

 analytical work is of no use. The obligation of the fertilizer control program 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 consumer or manu- 

 facturer. 



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

 half of one per cent or more are shown in red type. The names of the manufac- 

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

 numerically by formula, under the manufacturer. 



