CONFORMITY OF GUARANTEE 



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

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

 indicates the number of samples equaling or failing to meet guarantee : 



Number of samples analyzed 173 



Equalling or exceeding all guarantees 96 



Deficient in nitrogen only 39 



(9 subject to penalty) 

 Deficient in phosphoric acid only 11 



(2 subject to penalty) 

 Deficient in potash 10 



(6 subject to penalty) 

 Deficient in nitrogen and phosphoric acid 5 



(2 subject to penalty in both) 



(1 subject to penalty in nitrogen) 



(2 subject to penalty in phosphoric acid) 

 Deficient in nitrogen and potash 5 



(1 subject to penalty in both) 



(2 subject to penalty in potash) 



Deficient in phosphoric acid and potash 3 



Deficient in nitrogen, phosphoric acid and potash 4 



(1 subject to penalty in nitrogen and potash) 



(1 subject to penalty in potash) 



Thirty-five samples were guaranteed to contain magnesium oxide. Of these, 

 twelve indicated the guarantee in terms of water soluble magnesium oxide. In 

 these cases total magnesium oxide was not determined. With the exception of 

 two brands that were found slightly deficient all met the magnesium oxide guar- 

 antee. 



Penalties were assessed on 27 different lots of fertilizers representing 11 

 grades. Three grades, 0-15-30, 8-16-16, and 10-10-10 were involved in 17 of 

 the lots assessed. The others were scattering, one or two only of a particular 

 grade. The penalty clause was invoked in fourteen cases for nitrogen, six cases 

 for phosphoric acid and eleven cases for potash shortages. These cases are noted 

 in the table of analyses by bold type and by underline. The manufacturers are 

 listed alphabetically and the brand names by formula and alphabetically under 

 the name of the manufacturer. 



There are far too many small deficiencies as shown by the fact that only 96 

 out of 173 samples met all guarantees. This problem is of serious concern and 

 considerable co-operative work is underway to solve the problem. Fertilizers 

 are largely mixtures of chemicals. Segregation of these materials in the bag is 

 difficult to prevent. Modern methods of fertilizer 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 

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

 tical 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 care- 

 fully so that injustice will not be done to either the consumer or manufacturer. 



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