The process of manganese depositton in paddy soils |
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| Authors: | Hidenori Wada Ashara Seirayosakol Makoto Kimura Yasuo Takai |
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| Institution: | Faculty of Agriculture , The University of Tokyo , Tokyo , Japan |
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| Abstract: | Abstract The changes in quality and quantity of phenolic substances in the decaying process of rice straw in a soil were compared under moist and flooded conditions for 200 days. The amounts of phenolic substances divided into fractions of humic acid and fulvic acid, ether- and butanol-extractable and organic solvent-unextractable fractions, then the amounts of individual phenolic acids were determined. The following results were obtained. 1) Alkali-extractable total phenolics as well as individual phenolic acids decreased more rapidly under moist, than under flooded, conditions as rice straw decayed in the soil. The phenolics present were mainly attributable to the straw, not to the soil. 2) The decrease in the level of total phenolics in the early stage of the decaying process was mainly due to the decrease in ether-extractable phenolic compounds in the fulvic acid fraction, and in the later stage, was mainly due to the decrease in butanol-extractable phenolics in the humic acid fraction. 3) The amounts of butanol-extractable phenolics and organic solvent-unextractable phenolics were larger in humic acid than in fulvic acid. On the other hand, a larger amount of organic solvent-extractable phenolics, especially ether-extractable phenolics, was present in fulvic acid. 4) The degradation patterns and pathways of individual phenolic acids in the decaying process of rice straw in soil were found to be the lame as those of decaying straw without soil which were reported previously. 5) The level of phenolic substances in the humic acid was not greatly changed during the decaying process, but the phenolic substances in fulvic acid rapidly increased for 30 days and then rapidly decreased to a constant level. |
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| Keywords: | microbial ecology Mn-mottling bacterial growth |
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