MANURES. 41 



When this is done, the large dressing of lime will retain the 

 accumulating fertility, far beyond what the soil would be 

 capable of were it not for its agency ; and it is in this that 

 the great profit of farming consists. 



Large crops only are profitable. The market value of 

 many indifferent ones, will hardly meet the expense of cul- 

 tivation, and it is only the excess beyond this, which is pro- 

 fit. It is evident that if 15 bushels per acre of wheat, be 

 an average crop, and it requires 12 bushels to pay all ex- 

 penses of production, three bushels is the amount of profit. 

 But if by the use of lime and ordinary manures, the product 

 can be raised to 30 bushels per acre, the profit would be near 

 the value of 12 or 15 bushels, after paying for the manures. 

 Thus the advantage from good management, may be five 

 times that of neglect. This example is given as illustrating 

 a principle, and not as an exact measure of the difference be- 

 tween limed and unlimed fields. 



Application of Lime. Lime may be carried on to the 

 ground immediately after burning, and placed in small heaps. 

 There it may be left to slack by rains and the air ; after which 

 spread it preparatory to plowing. A good practice is to 

 place it in large piles, and cover it thickly with earth, which 

 gradually reduces it to powder. It may then be carried 

 where it is wanted, and spread from the cart. It is still bet- 

 ter, when small quantities only are wanted, to add it to the 

 compost, after it has been thoroughly air-slacked, avoiding 

 fermentation, as far as practicable, after it has been added ; as 

 its avidity for carbon expels the ammonia, which is the most 

 valuable of the volatile ingredients of the muck heap. A 

 thick coating of earth over the whole, will arrest and retain 

 much of the gas that would otherwise escape. Fresh burnt 

 lime does not act beneficially upon the crops during the first 

 year of its application, unless prepared by adding it to three 

 or four times its bulk of earth, in which condition it should 

 remain for a long time. If it be mixed with rich mold 

 when first taken hot from the kiln, it will decompose or libe- 

 rate the alkalies contained in the earth to such a degree, as 

 to render this compost a powerful manure. 



Nearly all limestones yield lime sufficiently pure for agri- 

 cultural purposes. When required of greater purity, it may 

 always be obtained by burning oyster shells, or others of ma- 

 rine origin. 



Magnesian Lime. Many of the limestones contain mag- 

 nesia, and are called ma<mesian lime. The effect of this, is 



