80 MARL. 



from the sun; yet I do not condemn the use of Marl 

 and other manures, when they can be obtained easily 

 and without too much expense. But if marl is to be 

 hauled from a distance of 5 or 10 miles, it is better to 

 let it remain; for it costs more than it comes to. I 

 advocate marl not as a manure, but as an ingredient 

 to improve the texture of the soil ; for there must be 

 a soil, or my system cannot be brought into operation. 

 Upon naked sand I can do nothing, and therefore I 

 recommend the use of marl, as it has a tendency to 

 bind together a sandy soil and to render a clayey one 

 more porous, by which the rains can be received and 

 retained. Clay marl for sandy land, and stone marl 

 for a clayey soil should be used. With this neces- 

 sary introduction, I shall proceed to speak of the 

 subject proposed ; the kinds and nature of marls. 



The component parts of marl are clay, sand and 

 calcareous matter. Sometimes two of them are united, 

 but chalk or lime in some proportion is always found. 

 Clay marls are found of various colors : blue, brown, 

 reddish, yellowish white and yellowish grey. The 

 blue clay marl is never found in conjunction with sand, 

 and the shell marl is not often found combined with 

 clay. There is in stone marl sometimes a super- 

 abundance of clay and sometimes of sand, though it is 

 more frequently sand. As observed before, the sand 

 marls, be it shell or shistus, should be put upon clayey 

 soils and clay marls on a sandy soil, because in the 

 first they render the soil more porous, and in the 



