NITRIFICATION 115 



limited a character to supply growing crops with all 

 of their available nitrogen. For general crop pro- 

 duction the organic matter of the soil is the source of 

 the nitrogen which undergoes the nitrification process, 

 and which furnishes food for the nitrifying organisms. 



139. Oxygen Necessary for Nitrification. The 

 second requirement for nitrification is an adequate 

 supply of oxygen. The nitrification organism belongs 

 to that class of ferments (aerobic) which requires oxy- 

 gen for existence. Oxygen is present as one of the 

 elements in the final product of nitrification as in cal- 

 cium nitrate, Ca(NO ) a . In the absence of oxygen 

 the nitrification process is checked. When soils are 

 saturated with water, the process cannot go on for 

 want of oxygen. Cultivation, particularly of clay 

 soils, favors nitrification increasing the supply of 

 oxygen in the soil. 



140. Moisture Necessary for Nitrification. Nitri- 

 fication cannot take place in a soil deficient in mois- 

 ture. As in all fermentation processes, so with nitri- 

 fication, moisture is necessary for the chemical changes 

 to take place. In a very dry time nitrification is ar- 

 rested for want of water. Water is as necessary to 

 the growth and development of the living organism 

 which carries on the work of nitrification, as it is to 

 the life of a plant of higher order. 



141. Temperatures Favorable for Nitrification. 

 The most favorable temperatures for nitrification are 

 between 12 C. (54 F.) and 37 C. (99 F.). It may 



