The chemistry of soil organic nitrogen: a review

1. From the data presented herein it is possible to deduce the following distribution of total N in humic substances and soils: proteinaceous materials (proteins, peptides, and amino acids) – ca. 40%; amino sugars – 5–6%; heterocyclic N compounds (including purines and pyrimidines) – ca. 35%; NH3–19%; approximately 1/4 of the NH3 is fixed NH4+. Thus, proteinaceous materials and heterocyclics appear to be major soil N components.