Characteristics of the qualitative composition of soil organic matter: Problems and solutions

The components of soil organic matter (SOM) such as lipids (waxes, fats, and resins), pigments (oxyanthraquinones and related substances, tetrapyrrole compounds and carotenoids), kerogen, glomalins, and hydrophobins are briefly described in the paper. In the traditional assessment of the qualitative composition of SOM, all of the above substances, as well as the products of hydrolytic destruction of detritus and partially decomposed plant material, pass into the alkaline solution. The resulting mixture, containing both specific and individual organic compounds, is usually subdivided into fulvic acids, hematomelanic and humic acids. It is proposed to revise the methodology for extracting various components of SOM. The new method should be based on the affinity of the SOM components for certain organic solvents and should allow the separation of humic substances and melanin from glomalin and hydrophobins.