by multiplying the pounds of nitrogen and phosphoric acid per ton 

 by the per cent of each grade and multiplying these products by the 

 trade values per pound for nitrogen and phosphoric acid. The 

 sum of the values of both ingredients in each grade gives the 

 comparative commercial value per ton. 



The column headed "percentage of difference 



Percentage of between selling price and valuation '' shows the 



Difference. percentage excess of the average retail cash price 



over the average valuation as figuredby our 

 trade values for 1907. The average comparative commercial 

 value of the 275 brands of complete fertilizers analyzed during 

 the season is $24.19, the average retail cash price is $35.40 

 and the percentage of difference 44.85. The above mentioned 

 column shows which fertilizers will furnish the largest amount of 

 plant food for a given outlay. They will be found to be those fertil- 

 izers where the percentage of difference is relatively small. Before 

 selecting a fertilizer on this basis however, care should be exercised 

 in choosing goods that are adapted to the crop and soil for 

 which they are to be used. It is well to bear in mind that in many 

 cases it is through accident that the percentage of difference is rela- 

 tively small on some of the fertilizers; imperfect or careless mixing 

 may be responsible for this. It is best therefore to get the general 

 standing of any particular brand for a number of years before mak- 

 ing a selection on this basis. 



Tile agricultural value of a fertilizer represents its 

 Agricultural crop-producing power which is far from constant on 

 Values. all soils. 



The beneficial effect of any fertilizer on a particular 

 soil depends on whether the fertilizer in question contains those 

 elements of plant food in suitable quantity and quality in which the 

 soil is deficient. In other words the supply of plant food in soils 

 varies widely and every user of commercial fertilizers must select 

 his fertilizer according to, the conditions of his soil and the require- 

 ments of the crop which he wishes to raise. We are often asked which 

 is the best mixed fertilizer to use. The consumer can better answer 

 this question for himself by a study of his soil conditions and crop 



