

CHAPTER II. 



ELEMENTS OF MANURES AND PLANTS. 



Manures are substances added or applied to 

 soils, to supply the wants of the different plants 

 intended for the use of man and animals. That 

 certain vegetable, animal and mineral substances 

 applied to soils will quicken the growth of vege- 

 tation and increase the amount of production, 

 are facts that have been known from the earliest 

 period. But the nature and properties of these 

 substances, called manures; the manner in 

 which they act; the best modes of applying 

 them ; and their relative value and durability, 

 are subjects still open to inquiry and discussion. 



Some substances used as manures furnish 

 directly the materials that enter into the com- 

 position of plants ; while others are applied to 

 change the physical character of the soil, and 

 effect chemical changes on the insoluble materi- 

 als that it may contain, rendering them soluble, 

 and in such condition that they can be assimila- 

 ted by plants. 



As every part of man and animals is originally 



