Characterization of soils in the ‘Bil’ environs of Brahmaputra Valley in Jorhat District, Assam for land use interpretation

The ‘Bils’ in southern bank of Brahmaputra valley in Jorhat district are in peripheral flood areas with the network of depression pools. The morphological, physical and chemical conditions of five dominant subgroups of Endoaquepts in the ‘Bil’ environs were studied to assess the pedoenvironment for adaptation of fishes. These soils have light grey to light brownish grey matrix and distinct yellowish brown to reddish mottles with high chroma (>4). The textural characteristics reveal that these soils are stratified with abrupt changes in fine sand, very fine sand, uniformity values and sand:silt ratio. These soils are slightly acidic (pH 6.8) to slight alkaline (pH 8.2) with irregular trends of organic carbon and calcium carbonate. The enrichment of organic carbon and pedogenic iron in B horizons was an indicative of subsoil deposit and rising of alluvial profile with respect to water table. The satelite data showed that these ‘Bils’ were littered with aquatic weeds and the remains of old flood plain features silted over. The pedo environment indicates that these ‘Bils’ are ideal for fish production but needs desiltation and regular removal of water weeds.