Humus composition of mountain soils in Central Japan with special reference to the distribution of P type humic acid

Abstract The central districts of Japan are mountainous areas rising to 3,000 metres which are predominantly covered with forest vegetation. A comprehensive and systematic classification of the soils in this region has not yet been made, but the following soil types have been reported to occur: - 1. 1. Brown forest soils, podzolic soils, black soils and red soils. [Described by OHMASA (14)]2. 2. Alpine grassland soils and alpine meadow soils. [Described by KUMADA et al. (9)]3. 3. A series of randzina-like soils with a very restricted distribution. These are derived mainly from limestone and show various degrees of maturity. [Described by KUMADA et al. (8)]4. 4. Red-yellow soils. These sometimes show a close resemblance to OHMASA's red soils and are found on diluvial plateaux and hills. [Described by KANNO (1)]5. 5. Paddy soils.