DECOMPOSITION OF OTHER NITROGENOUS SUBSTANCES 129 



organic substances), the liberation of the nitrogen in the form of 

 ammonia must always be considered in the light of the composition 

 of the organic matter as a whole. 



Decomposition of Nitrogenous Substances of a Non- 

 protein Nature.' — In addition to proteins and amino acids, 

 the plant, animal, and microbial residues commonly added to the 

 soil contain various other nitrogenous complexes, although in some- 

 what more limited amounts. These substances include nucleic 

 acids, alkaloids, purine bases, phosphatides, various amines, glu- 

 cose-amines and amid. Some of these and numerous other com- 

 plexes are actually produced in the soil by the various microbes 

 in the processes of synthesis of new cell substances. Some of 

 these complexes decompose readily; some more slowly. The 

 decomposition of uric acid takes place as follows: 



HN— CO 



OC C— NH. 



HN— C— NH/ 



Uric acid 



H2N 



I 



CO2 + OC CO— NH\ + 2H2O 



I I /CO > 



HN— CH— NH/ 



Allantoin 



CHO /HNo + 2H2O + O 



I + 20C< > 



COOH \NH2 



Glyoxylic Urea 



acid 



COOH + O 



2CO2 + 4NH3 + I > 2CO2 + H2O 



COOH 



Oxalic acid 



Under favorable aerobic soil conditions, calcium cyanamid 

 breaks down readily to urea and thence to ammonia: 



CaCN2 + H2O + CO2 -^ NH2-CN + CaCOs 



Calcium Cyanamid 



cyanamid 



+ 2HoO 

 NH2CN + H2O -> CO(NH2)2 > 2NH3 + H2CO3 



Cyanamid Urea 



