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PRINCIPLES OF AGRICULTURAL CHEMISTRY 



lime, (c) Ground Limestone: Ground limestone is more mild 

 in its action than quicklime and can be used in larger amounts. 

 The finer it is ground, the more effective it is. 

 CaO : 56 : CaCO 3 : 100 

 Lime Limestone 



One hundred parts of pure limestone contain 56 parts lime, 

 equivalent to 56 parts of pure burned lime, (d) Oyster Shells: 

 Oyster shells contain some plant food. They may be applied 

 unburnt and burnt, (e) Marl contains less lime than shells. All 

 forms of lime should be applied some weeks before planting. 



Quick lime is applied as a top dressing on land at the rate of 

 200 to 500 pounds per acre. Excessive applications of lime are 

 injurious. Ground limestone is used in larger quantity, particu- 

 larly when alfalfa is to be planted. One or two tons per acre of 

 ground limestone may be used every four to six years; even as 

 much as ten tons may be applied. 



Lime Liberates Potash. Lime releases absorbed potash, mak- 

 ing it more readily available to plants. Hence the lime would act 

 as an indirect potassic fertilizer. Boussingault 1 found the follow- 

 ing amounts of potash and lime removed by clover from a limed 

 and an unlimed soil, in Kg. per hectare. 



It does not follow from the above experiment that the lime 

 "released" potash. The liming made conditions more favorable 

 for the clover, and a larger crop was produced, with a heavier 

 draft on the soil. The availability of the plant food was not 

 necessarily changed because more of it was withdrawn from the 

 soil. 



It appears to be generally conceded that lime releases potash, 

 1 Storer, Agriculture. 



