COMMERCIAL FERTILIZERS 45 



form in which to apply lime. Air-slacked lime may also be 

 used when it can be obtained without too much expense. 

 Unslacked lime is not only more expensive than ground lime- 

 stone, but is likely to do more harm than good by destroying 

 the organic matter with which it comes into contact. If 

 limestone is applied, it should be at a rate of about two tons 

 per acre the first year, omitted the second year, and one- 

 half ton each year thereafter. Some farmers prefer to make 

 a larger application each four or five years. If water-slacked 

 lime is used, only three-fourths as much is needed. There 

 is some difficulty in applying lime to the land, but this has 

 been largely overcome by the use of lime spreaders especially 

 designed for this work. 



