Soils and Manures. 37 



ence to several circumstances — the chemical composition and 

 mechanical texture of the soil, the character of the climate or 

 season, and the kind of crop to be produced. The manures 

 most generally applicable are those composed of substances 

 which directly enter into and are essential to the growth of 

 plants. 



The fertihtj of a forest is not only maintained but increased 

 by the constant decay of its leaves, branches, and trunks, 

 which returns to the earth not only the nutritive matter origin- 

 ally drawn from it, but also much that has been supplied by 

 the atmosphere. This manure is just what the trees need — it 

 keeps good the supply of the elements essential to their growth. 

 So the parts of any plant decayed and rendered soluble are tlie 

 best manure for its species. But the products of our gardens 

 are mainly taken from them, and used as food. Every particle 

 not thus made use of should be returned, mixed with other 

 vegetable and animal matter, in the form of compost. For the 

 rest, stable manures (of which the dung of the horse is the best) 

 should be relied on as the grand staples. 



All the ordinarily cultivated plants, as has already been 

 stated, contain potash, soda, lime, magnesia, alumina, silica, 

 iron, sulphur, phosphorus, chlorine, carbon, oxygen, nitrogen, 

 and hydrogen. The four substances last named may, as we 

 have seen, be derived either immediately or remotely from the 

 air ; but they are all essentials of a fertile soil, and, to perpetu- 

 ate, its fertility under cultivation, must be supplied in the form 

 of manures. 



Stable Manure. — Common stable manure contains potash, 

 soda, lime, magnesia, alumina, silica, oxyd of iron, sulphur, 

 phosphorus, chlorine, carbon, oxygen, nitrogen, and hydrogen. 

 Lime exists both as a carbonate and as a phosphate, potash as 

 a muriate and a sulphate, and soda as a carbonate. A compari- 

 son* of this list of chemical substances with those enumerated 

 in the preceding paragraph as the essentials of a fertile soil, 

 will at once show the value of stable manure. Every part of 

 it has been formed from vegetable substances, and it has only 



