Commercial Fertilizers. 147 



lent physical condition of the soil, and the man who would ob- 

 tain best results without fertilizers is the one most likely to 

 realize a profit from their use. ' ' The fact that fertilizers can now 

 be easily secured, and the ease of application, have encouraged 

 a careless use, rather than a thoughtful expenditure of an equiv- 

 alent amount of money or energy in the proper preparation of 

 the soil. Of course it does not follow that no returns are secured 

 from plant food applied under unfavorable conditions, though 

 full returns cannot be secured under such circumstances. Good 

 plant food is wasted and the profit possible to be derived is 

 largely reduced. ' ' Again, in many instances, the ease with which 

 commercial fertilizers can be secured tends to a neglect of the 

 home resources and one far too commonly sees the waste of farm 

 manure and the purchase of commercial fertilizers practiced on 

 the same farm. 



What commercial fertilizers contain. Investigation and ex- 

 perience have shown that in most instances increased production 

 has resulted from the addition to the soil of but three of the 

 essential substances found in plants; namely: nitrogen, phos- 

 phoric acid and potash. It has been shown that in normal soils 

 there are probably sufficient quantities of all the other elements 

 which the plant requires. It was customary, soon after the time 

 of Liebig, for agricultural investigators to add all the elements 

 essential to plant growth, but practice soon showed that to be 

 unnecessary, for the reason stated above. Consequently com- 

 mercial fertilizers, as placed on the market today, contain only 

 nitrogen, phosphoric acid or potash, or mixtures of these ingre- 

 dients and these are the only elements giving the fertilizer com- 

 mercial value. 



Commercial fertilizers are made from a few basal materials 

 which are articles of commerce. Some of these materials contain 

 only one of the essential ingredients of a fertilizer, while others 

 contain two, but usually one is in such excess that the material 

 is used chiefly to furnish but the one element. 



The "complete fertilizer" consists of two or more of these 



