MANURES. 63 



manures. What remains to be said applies to lime, 

 marl, vegetable ashes, ashes of earth, and green 

 crops ploughed into the ground. 



It will be remembered that the action of lime, as 

 a manure, is owing to its causticity, or power of 

 dissolving animal and vegetable substances ; and to 

 its quality of absorbing carbonic acid from the at- 

 mosphere. These properties render it peculiarly 

 useful in composts, or mixtures of dung, peat, and 

 earth; a mass of which, disposed in alternate lay- 

 ers, is no doubt the perfection of this branch of 

 husbandry.* It is also applied without any acces- 

 sary, and with great advantage, to marshy grounds ;f 

 to those having in them the remains of shellfish ;J 

 to natural meadows, and to all soils abounding in 

 vegetable mould. On those of a different character 

 it must be cautiously used as to quantity, and, in- 

 deed, on any soil, an excess of it will completely 

 destroy the fertilizing principle ; an effect constant- 

 ly observed near mortar beds. 



The time of using it is liable to less uncertainty. 

 On wheat it should be sown as soon as the grain 

 shows itself, and on meadows late in the fall, and 

 after the cattle have been turned off. 



Marl, being a compound of clay and lime, has the 

 properties of the latter, and produces similar effects, 

 but in a smaller degree. Hence it is that the quan- 

 tity of it given to the acre is much greater than 

 that of lime. The English practice is to spread it 

 over a field to the depth of three or four inches. 

 This is done late in the fall, to the end that frost 

 and rain may break down and pulverize it. 



The properties of ashes, whether derived from the 

 combustion of animals, of vegetables, or of fossil 



* These might be formed in narrow lintals, inclining from 

 the stable. 



f After they have been drained. 



j There is much of this description of land on the bays and 

 creeks of the Chesapeake. 



