1-28 



FERTILIZERS 



The failure of clover on soils where it once grew is a 

 good indication of the need of lime, provided the failure 

 is not due to plant diseases or to a bad season. On the 

 other hand, a good stand of clover indicates positively that 

 the soil is sufficiently sweet. 



87. Forms and Application of Lime. Lime is obtained 

 from limestone rock. This rock is sometimes ground into 



PREPARING STONE LIME. 



Pulverized natural limestone is taking the place of other forms of lime as a 



fertilizer. 



fine particles, and then applied to the land. The fine 

 division of the rock is needed to spread it evenly and to 

 increase the relative surfaces of the particles in order to 

 hasten its action. But even in this ground form, lime- 

 stone rock acts very slowly, because it must first be dis- 

 solved in the soil. Often, therefore, limestone is heated 

 in a kiln, to drive off its carbon dioxide, and so changed 

 into quicklime. This is then slacked by air or water. When 



