OF AGRICULTURE. 215 



MARL. 



By the term, "marl," is generally understood an 

 earthly mixture, containing not less than one-fifth of 

 its weight of lime, or twenty per cent, of the carbonate 

 of lime. 



" Clay Marl." This has the appearance of a more 

 or less tenacious clay. When long exposed to the 

 air, or put in water, crumbles to powder. It has- 

 much the same qualities of lime, and acts in a similar 

 manner in soils, but with less energy. Clay marl 

 usually contains sixty- eight to eighty per cent, of 

 clay, and from twenty to thirty- two per cent, of 

 lime. 



"Stone Marl.^ Is often richer in lime than the 

 clay. Clay marls are sooner dissolved than the stone, 

 and commonly 'have stronger power of neutralizing 

 acids, and producing salts. Jlay or stone marls are 

 well suited to light, sandy soils, which they improve 

 and render more solid. On the contrary, sandy 

 marls are good for stiff, clay soils, causing them to 

 be easily worked, 



"Shell Marl." This marl is different in nature 

 from the two just described, being: highly fertilizing: 

 upon soils of every description. It does not disin- 

 tegrate in water like them, but sucks it up, and 

 sometimes swells like a sponge, as they do. It 

 contains from thirty-two to forty-six per cent, of 

 lime, and dissolves quickly when exposed to the 

 atmosphere. Most of the marls above described, are 

 to be found in great abundance in the Southern 

 States. From five to six hundred bushels to the 

 acre should be applied, or about twenty wagon loads. 



