406 SOIL PHYSICS AND MANAGEMENT 



Limestone when ground so that it will pass through a screen of 

 ten meshes to the inch makes an excellent material for applying to 

 the soil. The dust or finely ground limestone is ready for imme- 

 diate use, while the coarser part gives durability so that applica- 

 tions will not need to he made so often. 



The Best Form to Apply. Experiments have heen carried on 

 at some experiment stations to test the value of different forms. At 

 the Pennsylvania Station two tons of slaked lime once in four years 

 and of ground limestone every two years were used on different plots 

 and the total yields were greater for ground limestone. Analyses 

 of samples from each plot showed 375 pounds less of nitrogen for 

 the plot receiving air-slaked lime. Experiments at the Maryland 

 Station gave larger yields for ground limestone. 



REFERENCES 



1 Hilgard, E. W., Soils, 1906, p. 364. 



'Miller, M. F., Circular 69, Missouri Station, The Fertility of the Soil, 



1914, p. 6. 



Averitt, A. D., Bulletin 193, Soils of Kentucky, Kentucky Station, 1915, 

 p. 141. 



General References. Hopkins, Cyril G., Soil Fertility and Perma- 

 nent Agriculture, 1910. Van Slyke, Lucius L., Fertilizers and Crops, 1915. 

 Hall, A. D., The Soil, 1912. Whitson, A. R., and Walster, H. L., Soils 

 and Soil Fertility, 1912. 



