HIGH GRADK NITROGENOUS FERTILIZKR MATERIALS 49 



We have said that the substances containing nitrate nitrogen, am- 

 monia nitrogen and cyanamid nitrogen are 'sokible in water and 

 the organic nitrogen is insokible in water. The nitrogen as ni- 

 trates is ahvays the same and of equal vahie no matter from what 

 substance it is derived. The ammonia nitrogen is also of equal 

 value and equal quantities of it are as good no matter what 

 material it comes from. The soluble nitrogen from ammonium 

 sulphate, however, is not the same as the soluble nitrogen from 

 nitrate of soda and the insoluble nitrogen of organic materials 

 is not the same or of equal value. Therefore the source of 

 soluble and insoluble nitrogen makes a difference in value of the 

 forms oi nitrogen. The solubility of nitrogenous substances in- 

 fluences the availability, or the rate with which the nitrogen in 

 a suitable form is supplied so that the plant can assimilate it, 

 to some extent. 



The organic form of nitrogen is so called because the nitrogen 

 is combined with other elements as hydrogen, carbon and oxygen 

 in organic matter. Organic nitrogen is different in the various 

 substances. Some animal and vegetable materials are quite rich 

 in nitrogen while others do not contain much and are perhaps 

 not so valuable. Some organic substances may contain consid- 

 erable amounts of nitrogen but in such a locked-up state that they 

 are undesirable as plant food. 



When a substance gives up its nitrogen as nitrates readily we 

 say that the nitrogen is in a form that is active; it is quick acting, 

 quickly available, readily assimilated, etc. When the nitrogen is 

 locked-up we use the terms slow acting, slowly available, etc. 

 There are many degrees of availability of the different forms of 

 nitrogen and they range from the very quick acting of the soluble 

 materials to the organic materials that may take two or three 

 years or even longer before they give up their nitrogen for 

 plants to use as food. There are many organic substances that 

 contain nitrogen, but in such small amounts, or in such a locked- 

 up condition that they cannot be used profitably in the manufac- 

 ture of fertilizers. 



The principal sources of organic nitrogen will now be discussed. 



