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CHAPTER VIII. , 



OF MANURES. 



Necessity of m inures. Irrigation, its management and effect!. 

 Classification of manures : vegetable, animal, and mineral. 

 Vegetable manures : ploughing in of green crops, of straw, of 

 seaweed, etc.; advantage of these forms of -manure. Animal 

 manures : reasons for their remarkable efficiency. Animal 

 flesh, blood, wool, bones. 



SECTION I. OF THE NECESSITY FOR MANURES IN MOST SOILS. 



Having now considered the character of the soil, 

 and that of the crops in connection with each other, 

 we see that there is no hope of keeping up and in- 

 creasing the produce of any land, unless there is from 

 some source a supply of fertilizing substances to re- 

 store those that are carried away by the crops. Some 

 soils containing constantly decomposing rocks, or 

 peculiar springs, or subject to annual overflows where- 

 by enriching substances are deposited, need no other 

 foreign supply; but these are rare when compared 

 with those that require a constant and regular system 

 of addition, to render them properly productive. 



To the various manures employed for this purpose, 

 we shall now turn our attention. Before taking them 

 up in any regular classification, I may properly devote 

 a few words to one particular method of enriching the 

 soil, which cannot easily be brought into either of the 

 classes. I refer to irrigation. 



