Effectiveness of Fine Ground Limestone as compared with Hydrated 

 or Slaked Lime for Soil Improvement. 



Without going into the matter exhaustively, it may be said that most of the bene- 

 fits which follow the use of slaked lime on a soil may be duplicated by the use of ground 

 limestone when ground so that 80 to 90 per cent of the product passes through an 

 80 to 100 mesh sieve, and when applied in sufficient quantity to furnish the same 

 amount of calcium and magnesium oxides. It should 'be remembered that with a 

 limestone of this degree of fineness much of the product that passes a 100 mesh is 

 fine enough to pass a 200 mesh screen; further, that its effectiveness depends upon 

 the surface which is exposed to the action of the soil solution. The significance of this 

 is apparent when we apply the figures of Dr. H. E. Keiffer, which are to the effect 

 that a cubic foot of limestone ground to pass a 200-mesh sieve contains 8,000 times 

 more particles than when ground to pass a 12-mesh sieve; or, expressed in another 

 way, when applied to the soil at the rate of 1 ton per acre, the 200-mesh product fur- 

 nishes 13,869,051 pieces and the 12-mesh product only 17,337 pieces per square foot. ^ 



Degree of Fineness of Ground Limestone and Shell Lime on the 



Massachusetts Markets. 



With few exceptions the raw ground limestone products which are offered for 

 agricultural purposes to the Massachusetts trade are in a fairly satisfactory condition 

 as regards fineness. Of the brands which have been examined, there are but two 

 which are criticized at this time, and both of these are new products which have but 

 recently been placed on the market. These are the Producto Brand, put out by 

 Brewer & Company, and the shell dust lime of the Producers Sales Company. More 

 thorough grinding, so as to materially increase the amounts passing the finer mesh 

 sieves, would make these two products more effective. 



The chart on the opposite page illustrates graphically the fineness to which the 

 various brands of raw limestone and shell lime have been ground. 



Gypsum or Land Plaster. 



Although gypsum or land plaster is a lime compound used in agriculture, and for 

 this reason comes under the Massachusetts lime law and must therefore be inspected, 

 yet it should be borne in mind that this form of lime does not possess the property 

 of neutralizing soil acids. 



Two brands of gypsum were registered; one brand was collected and analyzed, 

 namely, the Ben Franklin Agricultural Gypsum (land plaster), registered and sold by 

 the United States Gypsum Company, Chicago, 111. It was guaranteed 85 per cent 

 calcium sulfate. It tested 86.44 per cent calcium sulfate, 5.03 per cent calcium carbon- 

 ate and .67 per cent magnesium carbonate. 



1 Nicholas Kopeloff: "The Influence of Fineness of DivLsion of Pulverized Limestone on Crop Yields as well 

 as the Chemical and Bacteriological Factors in Soil Fertility." In Soil Science, Vol. IV, pp. 19-67. 1917. 



