1 62 SYSTEMS OF PERMANENT AGRICULTURE 



lime, but there are other facts worthy of the most careful consid- 

 eration. 



Burned lime, whether fresh or hydrated, is known always as 

 caustic lime. According to Webster's Dictionary, the word caustic 

 means " capable of destroying the texture of anything or eating 

 away its substance by chemical action." This definition well 

 describes the action of caustic lime upon the organic matter of the 

 soil. The lime breaks down the organic compounds and unites 

 with the liberated carbon dioxid or other acid products. Not all 

 of the reactions involved are understood, but the general effect is 

 well known, and its long recognition in European countries has 

 given rise to the proverbial expressions, 



"Lime, and lime without manure, 

 Will make both farm and farmer poor," 



and " Kalk macht die Vater reich, aber die Sohne arm." (Lime 

 makes the fathers rich, but the sons poor.) 



Caustic lime is not only a powerful agent in hastening the de- 

 struction of organic matter, but it also has some power to increase 

 the solubility of phosphorus and potassium, all of which may be 

 of special help to legume crops; and if such crops are grown and 

 removed from the land and the decaying roots and residues used 

 as a further stimulant for the production of wheat, corn, or other 

 crops, more rapid progress can be made toward land ruin than 

 where no lime is used. 



On the other hand, even caustic lime can be used with profit if 

 ample provision is made to replace the organic matter destroyed 

 and also to restore the phosphorus (and potassium if necessary) 

 removed in the crops. 



The caustic action of slacked lime on the skin or flesh is familiar 

 to all, but a child can play in ground limestone as safely as in the 

 soil of the garden. 



The chief reason, and usually the only justifiable reason, for 

 applying lime to soils is to correct, or neutralize, soil acidity. The 

 fermentation and decay of nearly all forms of organic matter is 

 accompanied by the formation of acids, including carbonic acid, 

 nitric acid, and various organic acids, such as the well-known lactic 

 acid of sour milk, acetic acid of vinegar from apple juice, various 



