AGRICULTURAL EXPERIMENT STATION. 35 



excess of selling price over valuation in two cases does not 

 necessarily mean that one fertilizer is sold as cheaply as the other. 

 This can be illustrated as follows : A's fertilizer is sold for forty 

 dollars per ton, and values at thirtj'-two dollars. B's fertilizer sells 

 for twenty- four dollars per ton, and has a valuation of sixteen 

 dollars. The excess of selling price is eight dollars in both cases, 

 but this is only twenty-five per cent of the money value of the 

 ingredients in A's fertilizer, while it is fifty per cent of a similar 

 valuation of B's fertilizer. In other words, B is charging the 

 farmers twice as much as A for handling a given quantity of 

 plant-food. 



In studying the composition of fertilizers with reference to their 

 use the following points are important : 



1. The relative amounts of the different ingredients^ or what is 

 the same thing, the relative expenditure for the different ingredients. 

 It is to be noticed, for instance, that one superphosphate mentioned 

 in these tables contains 14 06 per cent of phosphoric acid, and 2.59 

 per cent of nitrogen, while another contains 8.35 per cent of 

 phosphoric acid and 5.73 per cent of nitrogen. In the former case 

 the valuation of the fertilizer is $29.14, and of this $18.18 is 

 derived from the phosphoric acid and $8.53 from the nitrogen. In 

 the latter case the total valuation is $32.80, of which the phosphoric 

 acid furnishes Sll.44 and the nitrogen $18.70. At whatever price 

 these two fertilizers are bought, in the one case about 62 per cent of 

 the price would be expended for phosphoric acid, and 29 per cent 

 for nitrogen, while in the other case these figures would be nearly 

 reversed, 35 per cent of the cost belonging to the phosphoric acid 

 and 57 per cent to the nitrogen. Whether it is wise for the farmer 

 to make the larger expenditure for phosphoric acid or for nitrogen 

 is determined by his needs, and with this question these analyses 

 and valuations have nothing to do. 



2. The condition of the phosphoric acid., whether largely available 

 or not. The total phosphoric acid in one of the fertilizers examined 

 this year is 11.17 per cent, of which only .48 per cent, or about one 

 twenty-third is in the insoluble form. In another fertilizer the 

 total phosphoric acid is 18.35 per cent, of which 13.69 per cent, or 

 about three-fourths, is insoluble. This means that the phosphoric 

 acid of one fertilizer is largely available at once, while the other 

 fertilizer will give up this ingredient to plants much more slowly. 

 This is an important matter, and if a market-gardener or sweet 



