20 



VERTICAL FARMING 



phorus, and lime, as these are at times deficient or else appear 

 to be deficient. Such elements as iron, aluminum, and silica 

 may be ignored, as they are nearly always present in sufficient 

 quantity to more than supply any demand made on them. 



For most agricultural conditions it is almost imperative that 

 the soil be not acid. The chief corrective for a sour cdndition 

 is lime, which is usually present in sufficient amounts for a 

 food, but in many soils is needed to overcome the sour condi- 

 tions produced by vegetable decay or bad drainage. It may be 

 added in several different forms. At present, carbonate of 

 lime or finely ground limestone or marble dust is largely used 

 for this purpose. This form is preferred by many on account 

 of there being no danger of trouble from an over-application. 

 Hydrated lime is also largely used, as is rock or quick lime. In 



Courtesy Charles Warner Co. 



MAMMOTH LIME KILN 



