PART IV. THE TRADE IN FERTILIZERS 



SECTION I. THE VALUATION OF 

 FERTILIZERS 



FOR very many years past it has been the habit to value 

 fertilizers according to the unit value system, in which it is 

 assumed that the value of the fertilizer is strictly in proportion 

 to the percentage of the important ingredients present. 

 Such a system by no means takes into account all the factors 

 concerned. From the manufacturer's point of view, ferti- 

 lizers cannot be produced by such a system, since the costs 

 of manufacture do not follow such rules. From the farmer's 

 point of view, the increased crop obtained does, more or less, 

 correspond with the increased percentage, since in practice 

 he would use such materials as were necessary to provide 

 him with a certain quantity of fertilizing ingredients. It is 

 not quite correct to say that fertilizing value is proportionate 

 to the percentage of fertilizing ingredient, since increasing 

 quantities of fertilizing material do not produce equivalent 

 quantities of crop increase. If a very small amount of any 

 fertilizing ingredient is added to the soil, the effect is fre- 

 quently very slight. It is with increasing amounts that 

 rapid increase in crop production follows, but ultimately 

 a limiting value is approached, and further additions of 

 fertilizing materials will produce no corresponding increase 

 in crop, a condition of affairs which is commonly explained 

 by " the law of diminishing returns. ' ' If increasing quantities 

 of fertilizing material are still added to the soil, injury may 

 be done, and the crop returns become even less. In practice 

 the farmer tends to use rather lesr fertilizer than is capable of 

 producing the most economical results, and therefore at the 

 stage of development which is commonly reached in the 



