68 FIELD AND LABORATORY STUDIES OF SOILS 



useful purpose. Soils that are lacking in lime are usually 

 sour or acid and will not produce a full crop until lime 

 has been applied to kill the acid. If a soil turns the lit- 

 mus paper red and refuses to grow good clover, it should be 

 treated with a ton or two of fine-ground limestone. If 

 the soil bubbles freely when hydrochloric acid is appHed, 

 no lime is needed. 



A 



