Abstract
Humus characteristics of Ando soils during secondary succession were studied at Sugadaira, Central Japan. 1) The values of color density (CD) of NaOH extractable humus decreased, and the Δlog K values increased during secondary succession. 2) The amounts of humic acid fractions in the Miscanthus sinensis grassland soils were greater than those in the red pine forest soils. 3) The Δlog K values of humic acid fractions ranged from 0.52 to 0.56. And the RF values of humic acid fraction in the lower parts of A horizons were higher than those in the upper parts. 4) The RF values of humic acid fractions decreased during the secondary succession. It seemed that the decrease of the RF values related to the pedogenesis of degraded black soils.
