Manures. 401 



Vegetation : 1st, by killing predatory vermin and weeds; 2dly, 

 by promoting the decomposition of stubborn organic remains 

 m the soil ; 3dly, by protecting incumbent plants from violent 

 revolution of temperature. 



All these properties seldom, if ever, occur in one species of 

 manure, but each is usually particularised by possessing one 

 or more in a superior degree. That is the most generally 

 applicable manure that is composed of matters essential to the 

 growth of plants ; the chief of these are carbon, hydrogen, and 

 oxygen, therefore all animal and vegetable substances are ex- 

 cellent manures. It would evidently be of great benefit, if 

 every plant could be manured with the decaying parts of its 

 own species ; the ancients made this a particular object in some 

 parts of their agriculture. We read that those vines were 

 the most fruitful, which were manured with their own leaves 

 and prunings and the skins of expressed grapes. (Crescentius 

 Agric, § 2. c. 6.) This rule might be so far followed, as that 

 the stems of potatoes, peas, &c, could be dug respectively 

 into the compartments where those crops are intended to be 

 grown in the following year. 



The following table shows the relative constitution of com- 

 mon stable manure and our usual crops : — 



Stable Manure. Crops. 



Carbon, ) 



Hydrogen, > These are chief components of all plants. 



Oxygen, ) 



Nitrogen, - - In some vegetables. 



Carbonate of lime. In almost all plants. 



Carbonate of soda, 



Benzoate of soda, 



Muriate of potash, In cucumbers, garlic, &c. 



Muriate of soda, - Perhaps in all plants. 



Sulphate of soda, 



Sulphate of potash, In cucumbers, garlic, &c. 



Magnesia, - In all corn, and many other plants. 



Phosphate of lime, Potatoes, onions, &c. &c 



Oxide of iron, - In most plants. 



Imc" ina ' } ^ ™°st plants. 



Stable manure, and for the same reason every other manure 

 composed of animal or vegetable remains, is evidently valuable 

 to plants, by affording them such matters as they are com- 

 posed of. But this is not the only reason that manures are 

 beneficial; for in that case mere decayed parts of their own 

 species should be the most fertilising applications. There is 

 no doubt that plants are essentially benefited by such appli- 

 cations.; but why do potatoes, for example, grow more luxu- 



Vol. III. — No. 12. d D 



