Humification microorganisms

Soil and related environments are both an important natural habitat of biota and a natural reservoir of biotic debris consisting of plant remains and dead animals and microorganisms. With time, dead remains are subject to continuous turnover, either mineralized or transformed to diverse organic components which are termed humus. This process is referred to as humification. Humus is composed of humic substances plus nonhumic substances that have become stabilized and are thus an integral part of soil and related environments (Table 2.1). 

The term biochemical stabilization refers to the biotic or abiotic production of organic substances that are refractory to decomposition by microorganisms and contribute, through condensation and complex formation, to the stabilization of otherwise easily decomposable substrates such as enzymes. This stabilization process coincides with the process of humification. 

V. R. Williams (1914), a well-known Russian investigator, also postulated the existence of two stages in the humification process, the first being the decomposition of the original plant residues to simpler compounds, and the second heing the synthesis of substances of a more complex nature. In contrast to the views of Maillard, both processes were believed to result from the enzymatic activity of microorganisms. 

The microorganisms surrounding the roots are active in the breakdown of any crop residues or other energy sources, and in the overall humification process. Since the rhizosphere organisms are known to be more active than are those located elsewhere in the soil mass (Katznelson, 1960), it follows that this humification process in the rhizosphere is accelerated at least to the extent that the numbers are increased. Starkey (1931a) observed such a correlation. 

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