The Role of Microorganisms in the Transformation of Organic Matter in Forest Soils

Autor: Florence G. Tenney, Selman A. Waksman, Kenneth R. Stevens
Rok vydání: 1928
Předmět:
Zdroj: Ecology. 9:126-144
ISSN: 0012-9658
DOI: 10.2307/1929350
Popis: According to Ramann, one of the earliest students of forest soils, the biology of the soil comprises all the changes that take place there under the influence of organic life. A study of the microbiological processes in the soil should, therefore, comprise not only the determination of the microscopic population but also of the various transformations brought about by numerous members of this population in the soil. The chemical changes thus brought about in the organic and the inorganic constituents of the soil giving rise to the so-called " forest humus " represent rather difficult problems in organic chemistry; this is largely the reason why so little progress has been made in our understanding of the nature of the biological processes in forest soils and their r6le in the nutrition of higher plants. A large number of the investigations dealing with the functions of microorganisms in forest soils can be grouped around the transformation of nitrogen. Even the soil organic matter or " humus," commonly spoken of as either " raw humus " or as " mull " depending upon the conditions of its formation, has been considered only as far as it formed a source of available nitrogen in the soil; among the products of decomposition of this organic matter ammonia and nitrate have usually been determined, the latter being produced only under certain conditions. The numerous other soil processes attracted no attention at all or have been considered only in a very general way. The nature of the fixation of nitrogen in forest soils, for example, has remained very vague, since neither Azotobacter (Weis and Bornebusch '17) nor legume bacteria are found to occur to any extent in these soils, especially in the " raw humus " soils. The transformation of the non-nitrogenous complexes of the soil organic matter, if investigated at all, has been limited to a study of the liberation of carbon dioxide, which is evidently essential for tree growth. The decomposition of celluloses, hemicelluloses including pentosans, lignins, resins, tannins, and the various other non-nitrogenous constituents of the forest plant residues attracted only little attention. Whatever is known of these processes in forest soils has resulted either from the investigations by plant pathologists on the activities of parasitic and semi-parasitic fungi (Hartig '78, Ward '98), or from the work of wood technologists on the decomposition of wood by pure and mixed cultures of fungi, or by the interpretation of bacteriological and other microbiological processes in field and garden soils.
Databáze: OpenAIRE
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