2O4 THE FIRST BOOK OF FARMING 



should be in the hands of every farmer who makes 

 a practice of using commercial fertilizers. 



The manufacturers of fertilizers comply with the 

 law by printing on the bag or package the per cents 

 of plant food in the fertilizers, and these statements 

 in the great majority of cases agree favorably with 

 the analyses of the experiment stations, but they do 

 not in all cases state what materials were used to 

 furnish the different kinds of plant food, and it is 

 not always possible to find this out by analysis. 



Low grade materials. 



For instance in mixing a fertilizer one manufac- 

 turer may use dried blood to furnish nitrogen and 

 another may use leather waste or horn shavings. 

 The latter contains more nitrogen than the dried 

 blood, but they are so tough and decay so slowly 

 that they are of little benefit to a quick growing 

 plant. 



Inflating the guarantee. 



Although the dealer states correctly the per cents 

 of plant food in the fertilizer, he is quite frequently 

 inclined to repeat this in a different form, and thus 

 give the impression that the mixture contains more 

 than it really does. 



The dealers also give the nitrogen as ammonia 

 because it makes a larger showing. 



Phosphoric acid is often stated as " bone phos- 

 phate " because in this the amount appears to be 

 greater. 



For example, an analysis taken from a fertilizer 

 catalogue reads as follows: 



