88 DEPARTMENT OF AGRICULTURE GEORGIA. [374] 



The principal mineral elements obtained from the ash of 

 plants, are sulphur, phosphorus, silicon, chlorine, potassi- 

 um, sodium, calcium, magnesium, iron and manganese. 

 Oxygen and carbon are also found in small quantities. 

 These, together with nitrogen and hydrogen, constitute all 

 the important elementary substances found in agricultural 

 vegetation. 



But few of these substances are utilized by plants in their 

 elementary forms, oxygen being probably the only one. 

 Sulphur is taken up by plants as sulphuric acid, silicon as 

 silica, chlorine in the form of chlorides, potassium as po- 

 tassa or potash, sodium as soda, calcium as lime, magne- 

 sium as magnesia, iron and manganese as oxides of these 

 metals, carbon as carbonic acid, nitrogen as ammonia and 

 nitric acid, oxygen in its free state and in various com- 

 binations, hydrogen in water and ammonia. This is not 

 intended as an exhaustive enumeration of the forms in 

 which these substances are taken up by plants, but only to 

 show that, with the exception oi free oxygen, they are ap- 

 propriated from their various compounds, instead of from 

 their elements. 



These ash elements are essential to the full development 

 of plants ; the total absence of any one of them being fatal 

 to their very existence. In this sense, therefore, they are 

 of equal importance to vegetation. 



In another sense, however, some have much greater im- 

 portance to the agriculturist than others. It is unnecessa- 

 ry to consider those elements, which are derived from the 

 atmosphere, since its composition is practically beyond 

 man's control. It is with the soil that the farmer must deal, 

 and on his knowledge and skill in treating this, his success 

 will depend. The term Agriculture, means the cultivation 

 of the soil, but its cultivation does not embrace the full 

 scope of the farmer's duty, though an important part of it. 



He must not only acquaint himself with the physical pe 

 culiarities of his soil, and learn to remedy its defects, but 





