Studies on the Physical Properties of Some Assam Soils in Relation to Their Erodibility

The physical properties in relation to the erodibility of recent alluvial, old alluvial, hill and forest soils of Assam were studied. The hydraulic conductivity, water stable aggregates, mean-weight diameter and moisture equivalent were found to be lowest in the recent alluvial and highest in the forest soils while in the old alluvial, and hill soils these were found to be intermediate. On the other hand, erosion ratio, dispersion ratio, suspension percentage, clay ratio and silt/clay ratio were found to be highest in the recent alluvial and lowest in the forest soils and intermediate in the other two soils. According to the erodibility, the soils have been ranked as recent alluvial > old alluvial > hill soils > forest soils. The hill soils and the forest soils have been found to be non-erodible while the recent alluvial and the old alluvial soils were found to be erodible requiring proper soil conservation measures. In all the soils, the subsurface soils were found to be relatively more erodible than the surface soils.