CHAPTER IV. 



ON MANURES. 



Art. XXXIII.— on THE PRINCIPLES OF ARTIFICIAL 

 MANURING. 



By Baron Vox Liebig. 



If we compare the experience of farmers regarding- the fer- 

 tiHty of the soil and the quantity of its productions, we are 

 surprised by a result which surpasses all others in general 

 application and uniformity. 



It has been observed, that in every part of the globe where 

 agricultxu'e is carried on, in all varieties of soil, and with the 

 most different plants and modes of cultivation, the produce of 

 a field on which the same or different plants have been culti- 

 vated during a certain number of 3^ears, decreases more or 

 less in quantit}', and that it again obtains its fertility by a 

 supply of excrements of man and animals, which generally 

 are called manure ; that the produce of the fields can be 

 increased by the same matters, and that the quantity of the 

 crop is in direct proportion to the quantity of the manure. 



In former times, scarcely any attempt was made to account 

 for the cause of this curious property of the excrements of 

 man and animals. Without taking into consideration the 

 origin of the excrements, and the relation the}^ bear to the 

 food, it was not astonishing that their effect was ascribed to 

 fi remnant of vital power, which should qualify them to 

 increase the vitality in plants. Ascribing their influence on 

 the fertility of the fields to an incomprehensible occult cause, 

 it was forgotten that every force has its material substratum; 

 that with a lever, in a mathematical sense, which possesses 



