240 SOIL ACIDITY AND LIMING 



In sections far from railroads and from limestone-pulverizing 

 plants, and in which outcrops of good limestone occur, farmers 

 may find it much more economical to pulverize their own limestone 

 by using small pulverizing machines (Fig. 157). Limestone is 

 often found on farms where the fields are acid (Figs. 158 and 159). 



FIG. 155. Limestone pulverizers are built on the swing-hammer principle. 



Limestone screenings from crushed rock are frequently used 

 for liming. Sometimes this material is as fine as pulverized lime- 

 stone, but more often it is rather coarse, and hence slow acting. 



Magnesian limestone in general is equally as good as pure 

 limestone for liming. 



Pulverized limestone is considered best to use on sandy soils. 



