Plants can take up Nitrogen only in the form of Nitrates 

 that is, in combination with alkaline base, such as lime or 

 sodium. 



The Nitrogen contained in all fertilizers, with the ex- 

 ception of Nitrate of Soda, must first be nitrified that is, con- 

 verted into Nitrate before the plant can take it up. This 

 nitrification is always attended with greater or less loss of Ni- 

 trogen. 



A sufficiency of lime in the soil hastens nitrification, 

 while a scarcity of lime retards it. Nitrate of Soda is the only 

 nitrogenous fertilizer that will do its work perfectly without 

 lime, because it already contains Nitrogen in a form that is 

 capable of absorption by plants. 



Leguminous plants assimilate free Nitrogen from the air 

 through the medium of the micro-organisms inhabiting the 



