378 



NATUEE AND PROPEKTIES OP SOILS 



thor indicate that while the coarser lime is less rapid in its 

 action, it remains in the soil longer and its influence should 

 be effective for a greater period of years. 



Table LXXXV 



decomposition of limestone during the three years 



after application. 





Percentage op Decomposition 



Mesh 



High Calcium 

 Stone 



High Magnesium 

 Stone 



100 mesh and smaller. 



60 to 80 mesh 



20 to 40 mesh 



8 to 12 mesh 



92.4 

 81.5 

 46.7 

 14.9 



91.2 



72.2 



34.9 



5.9 



The conclusion is likely to be drawn that limestone should 

 be ground as finely as possible. Such an assumption is at 

 fault in several ways. In the first place, very fine lime is 

 difficult to handle and unpleasant to distribute. Again, the 

 cost of grinding increases very rapidly with the fineness, being 

 entirely too expensive compared with the results attained. 

 Moreover, finely ground material does not possess the lasting 

 qualities of the coarser lime. Because of the cost of grinding 

 the stone to a very fine condition and the rapidity with which 

 such material disappears from the soil, a medium ground 

 lime seems to be a more desirable commercial product- Such 

 material has enough of the finer particles to give quick re- 

 sults and yet enough of the coarser fragments to make it last 

 over the period of the rotation. A pulverized limestone, all 

 of which will pass a 10-mesh sieve, 70 per cent, of which 

 will pass a 50-mesh sieve and 50 per cent, of which will pass 

 a 100-mesh sieve, should give excellent results and yet be 

 cheap enough to make its use worth while. 



The following figures show in an approximate way the 



