LIMING THE SOIL 



377 



is not the only importance of jfineness. Lime produces its in- 

 fluence largely through contact, and the finer the lime is 

 ground, the more thorough is the mixing with the soil and 

 the greater the number of operating f ocii. 



"White ^ presents the following significant data as a result 

 of certain laboratory and greenhouse studies at State College, 

 Pennsylvania. 



Table LXXXIV 



A COMPARISON OF VARIOUS GRADES^ OF LIMESTONE WHEN 

 APPLIED AT THE SAME RATES. 



Conditions 



100 Mesh 



AND 



Smaller 



60-80 

 Mesh 



20-40 

 Mesh 



8-12 



Mesh 



Solubility in carbonated water. 

 Value in correcting acidity .... 



Formation of nitrates 



Plant growth 



100 

 100 

 100 

 100 



57 

 57 

 94 

 69 



45 



27 

 56 

 22 



28 



18 



12 



5 







These figures show that the finer grades of limestone are 

 much more rapidly effective. Further data by the same au- 



=^ White, J. W., The Value of Limestone of Different Degrees of Fine- 

 ness; Penn. Agr. Exp. Sta., Bui. 149, 1917. Also, Thomas, W., and 

 Frear, W., The Importance of Fineness of Sub-dimsion to the Utility of 

 Crushed lAmestone as a Soil Amendment; Jour, Ind. and Eng. Chem., 

 Vol. 7, ISTo. 12, pp. 1041-1042, 1915. 



Broughton, L. B., et al. Tests of the Availability of Different Grades 

 of Ground Limestone; Md. Agr. Exp. Sla., Bui. 193, 1916. 



Kopeloff, N., The Influence of Fineness of Division of Pulverized 

 Limestone on Crop Yield as Well as the Chemical and Bacteriological 

 Factors in Soil Fertility; Soil Sei., Yol. IV, ISTo. 1, pp. 19-67, 1917. 



Frear, W., The Fineness of Lime and Limestone Application as Be- 

 lated to Crop Production; Jour. Amer. Soc. Agron., Vol. 13, No. 4, 

 pp. 171-174, 1921. 



^Lime is graded by sieves carrying a certain number of meshes to the 

 linear inch. An 80-mesh sieve has 80 openings to the linear inch or 6400 

 to the square inch. Screens rated as carrying the same number of meshes 

 often do not give the same grade of material, due to a difference in the 

 size of wire used. Material of 60 to 80 mesh refers to those sizes that 

 will pass through a 60-mesh but will be held by an 80-mesh screen. 

 A standardization of sieves and methods of expressing such analyses is 

 much needed. 



