140 Fertilizers 



this element is concerned, is usually mixed with more or 

 less dirt and other impurities, and is, therefore, not as 

 rich in lime as that derived from pure limestone. When 

 properly burned, it contains from 80 to 90 per cent of 

 actual lime. 



Ground oyster shell lime is an excellent source of lime, 

 containing from 85 to 95 per cent of calcium carbonate, 

 equivalent to 48 to 53 per cent actual lime. This product 

 also contains minute quantities of nitrogen and phosphoric 

 acid. In some cases as much as seventy-five cents' worth 

 of these elements is contained in a ton of the material. 

 Ground oyster shell lime decomposes very readily in the 

 soil, and the fineness of division is not such an important 

 factor in determining its value as it is in the case of ground 

 limestone. 



Shell marl. 



Shell marl is one of the less important sources of lime. 

 There are a number of deposits in Atlantic coast states, 

 but few of these are worked. This product varies much in 

 its content of lime according to the amount of impurities 

 laid down with it, though it often contains as high as 95 

 per cent of calcium carbonate, equivalent to 53 per cent 

 of actual lime. When it may be secured reasonably, it 

 is one of the best forms of lime, because it is really a 

 material which was at one time in solution, and hence, its 

 extreme fineness of division makes its action immediate 

 and complete. 



ACTION OF LIME IN SOILS 



Lime has already been referred to as a plant-food. Its 

 indirect actions are numerous, producing many specific 



