A POSSIBLE SOURCE OF HUMIC ACIDS IN VOLCANIC ASH SOILS IN JAPAN—CHARRED RESIDUE OF Miscanthus sinensis

We compared the physicochemical and spectroscopic properties of humic acids obtained from the charred residue of Miscanthus sinensis Anderss and the A horizons of volcanic ash soils in Japan. The elementary composition, Δlog K and RF values, UV, visible, and IR absorption spectra, and x-ray diffraction pattern of the acids are similar to those of the soils. The findings indicate that the charred residue of Miscanthus sinensis deserves attention as a possible source of humic acids with a high degree of darkening in volcanic ash soils in Japan.