26 Fertilizers 



THE USEFULNESS OF A FERTILIZER CONSTITUENT DOES 

 NOT DEPEND UPON ITS ORIGINAL SOURCE 



It should be remembered, too, that artificial manures 

 or fertilizers supply plant-food just as well as other and 

 more common products. The fact that the food exists 

 in substances other than those which are familiar to the 

 farmer, is no evidence that it may not be quite as good, 

 or even better, than when contained in his home-made 

 products. It is not the outward appearance of a sub- 

 stance, but the kind and form of the elements contained 

 in it, that measures its value as a fertilizer. 



For example, the nitrogen that may be applied in 

 the form of a commercial fertilizer exerts no different 

 function in the plant than that which may be acquired 

 from the original soil, or from materials that have recently 

 been obtained from that soil, and again returned as yard 

 manure. The same is true of phosphoric acid and 

 potash. In their concentrated, artificial forms, they serve 

 to feed the plants in exactly the same way, and exert the 

 same function in them, as those contained in the soils 

 themselves, or that may be contained in wood ashes, or 

 materials more familiar, or of more common occurrence. 

 The form in which they exist when applied does not 

 necessarily imply that they are stimulants rather than 

 food, though frequently, because of their form, the plants 

 are able to absorb them more readily, and thus by their 

 rapidly increased growth, encourage a belief that an un- 

 due stimulating effect accompanies their use. The fa- 

 mous experiments of Lawes and Gilbert, at Rothamsted, 

 England, teach this one thing very emphatically; viz., 

 the efficiency of chemical fertilizers as compared with 

 yard manures. 



