抄録
In Vietnam, Fluvisols are distributed mainly in the agro-economic zones of the Red River and the Mekong River Deltas and consist of some soil units. Clay mineralogy was studied for five pedons of Fluvisols collected in these agro-economic zones: two from the Haiphong coastal plain, one from the Red River plain and one from the Thaibinh River plain of the Red River Delta, and one from the Mekong River plain of the Mekong River Delta.
Mica was a predominant mineral with contents ranging between 21 and 50% in the <2μm clay fraction. Mica, and chlorite and kaolinite with lesser amounts were present in all the pedons examined. Minor amounts of smectite and vermiculite were detected in one pedon of the Red River plain. Two kinds of mixed-layer minerals were identified. The mica/vermiculite/smectite mixed-layer mineral was identified in two pedons of the Haiphong coastal plain. The vermiculite/smectite mixed-layer mineral was identified in two pedons of the Thaibinh River and the Mekong River plains, and chlorite-vermiculite intergrade was present in the top layer of these pedons.
The inherent potentiality of Fluvisols as paddy cultivation was evaluated based on the particle-size distribution and the nature and amount of minerals in the clay fraction. Among the five Fluvisols examined, it was high for Fluvisols of the Mekong River plain, medium for those of the Haiphong coastal plain and the Thaibinh River plain, and low for that of the Red River plain.
