LIME 



191 



249. Caustic lime versus ground limestone. — As lime 

 helps to correct soil acidity no matter in what form it is 

 applied, there is little advantage in one form over another 

 so long as it is remembered. that 100 pounds of ground lime- 

 stone are equivalent to 56 pounds of freshly burnt lime, and 

 provided the cost, hauling included, is in that ratio. The 

 greater ease with which ground limestone may be handled 

 would, under these circumstances, give it the preference. 



In respect to its effect on tilth, lime, in the caustic form, 

 is apparently more effective than when in the form of ground 

 limestone. For heavy clay soil, the compact and cloddy 

 condition of which presents a serious difficulty, caustic lime 

 is preferable. A comparison of these two forms of lime on a 

 heavy clay soil is shown in the following table in which the 

 average percentage increase in crops from the limed over the 

 unlimed plats for a period of five years is stated. 



Table 41. — Average Percentage Increase in Yield Due to 

 Caustic Lime and Ground Limestone 



Form of Limb Applied 



Caustic lime 



Ground limestone . . . . 



Caustic lime 



Ground limestone . . . . 

 Caustic magnesian lime . . 

 Ground magnesian limestone 



Pounds 

 Applied 

 per Acre 



3000 

 6000 

 1000 

 2000 

 2000 

 3225 



Percentage 



Increase in 



Yield of 



Crops 



20.9 

 14.8 

 3.9 

 3.7 

 6.7 

 3.3 



250. Fineness of grinding limestone. — The greater 

 solubility of finely ground material, as compared with coarse, 

 makes it desirable that limestone be at least fairly well 

 pulverized before it is used. If it is so ground that all of the 

 particles will pass through a sieve having 50 meshes to the 



