Microbiological changes in flooded soils
1962
MITCHELL, R. | ALEXANDER, M.
Soil flooding is a common practice in crop production and in measures designed for the control of certain plant pathogens. Because of the alterations in the moisture, aeration, and nutrient status of the soil, as a consequence of such practices, marked microbiological changes take place. These changes in the microflora are both qualitative and quantitative. Among the apparently selective effects of flooding are the eradication of fungi such as Sclerotinia sclerotiorum (9) and nematodes like Heterodera marioni (2). Flood-fallowing, moreover, has been proposed as a means for the elimination from soil of Fusarium oxysporum f. cubense (11).The specific mechanisms by which the microbiological changes are brought about are unknown. That the reduction in population size or complete elimination of some specific microorganism is the result of microbial reactions is apparent from the significant suppression of the test species in non-sterile as contrasted with sterile soil. The effects of O2 depletion through microbial metabolism (10) or the influence of bacterial toxins (3) have been suggested as means by which indigenous microorganisms may affect the persistence of alien species. In the present investigation, a detailed study of the ecological changes in submerged soil was initiated to provide a better understanding of the principles involved in the control of specific fungi by soil submergence.
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