FERTILIZERS 



limited, as is the case where they are grown in 

 pots, it soon becomes exhausted and the neces- 

 sary elements must be supplied either by the 

 addition of fresh soil or by treating with some 

 soluble plant food. (Fig. 14.) 



APPLICATION OF FERTILIZERS 



Fertilizers may be applied either by mixing 

 directly with the potting soil or in liquid form 

 when the plant has become well established. 

 Fertilizers which require decomposition to 

 render their constituents available must be 

 added to the soil. 



KINDS OF FERTILIZERS 



Fertilizers are of two kinds known as natural 

 manures and chemical fertilizers. By natural 

 manures are meant the cleanings from horse- 

 stables, cow-barns or hen-coops, mixed with de- 

 caying vegetable remains of various kinds. 



When added to the soil natural manures serve 

 two functions. First, they add directly to the 

 available soil supplies of potash, phosphates and 

 nitrogen; second, natural manures, and espe- 



51 



