CHAPTER XIV 



NITRIFICATION: NITROGEN MADE READY FOR 

 PLANTS 



Every one familiar with the growing of crops knows 

 that organic matter, when thoroughly decomposed and 

 mixed with the soil, increases the producing power of 

 the land ; especially is this the case when nitrogen com- 

 pounds are present in considerable quantities. 



We have discussed the manner in which organic mat- 

 ter is decomposed in the soil. Bacteria do the work : 

 they break into pieces every sort of organized life. A 

 question now arises : What becomes of these simpler 

 forms, now pulled apart and disorganized? One phase 

 of this question has been answered already : some of the 

 nitrogen has been given freedom : it has disappeared 

 from the soil. The mineral substances, that were con- 

 tained in the organic matter, are left in the soil. They 

 cannot get away into the air. They will be available at 

 once to plants, or else lost through drainage waters. 

 They may join with other elemental forms already in the 

 soil, and so remain until called into use by the enticing 

 demands of future generations of plants. 



The carbon compounds remain either in the soil or re- 

 turn to the air as rapidly as they are released from their 

 combinations by decomposition bacteria. This departure 

 may be in the form of marsh gas or of carbon dioxide. 

 In either case, it offers no service to growing plants so 

 long as it remains in the soil. 



We now reach the important part of our question, and 

 out of it grows a second. What becomes of the nitrogen 



