Behavior of phenolic substances in the decaying process of plants

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Abstract
Phenolic compounds in the soils collected from 6 paddy fields and 9 forests were surveyed quantitatively by gas chromatography. The results are as follows: 1) p-Coumaric, ferulic, vanillic, p-hydroxybenzoic, syringic, salicylic, and protocatechuic acids were detected in all soils. Among these acids, p-coumaric acid was present in the largest quantity in most of the soils. Gallic, caffeic, and sinapic acids, resorcinol, and phloroglucinol were not detected. 2) The total amounts of individual phenolic acids in the forest soils (34-632 ppm) were markedly higher than those in the paddy soils (10-26 ppm). p-Coumaric acid content went up to 188 ppm in the forest soils and up to 7 ppm in the paddy soils. The average concentration of total phenolic acids per weight of organic matter in the forest soils was about 2 times as high as that in the paddy soils. 3) In the paddy soils, the concentrations of p-hydroxybenzoic, vanillik, syringic, p-coumarie, and ferulic acids, which have no chelating ability, were considerably related to the pH and the carbon content of the soil, but the concentrations of protocatechuic and salicylic acids, which are chelating agents, were not related to those of the soil. Also in A horizons of forest soils, the concentrations of many phenolic acids were related to carbon content, but not to pH. 4) In a forest soil surveyed, the concentrations of individual phenolics decreased with increasing depth. However, the ratios of the amounts of individual phenolics to the carbon content increased with depth.