Capability and quality assessment of rice growing hydric soils in majuli river island, assam, India

Abstract

The  wetland soils in  majuli island is a unique in maintaining rice ecology and geoenvironment in Brahmaputra valley of Assam  due to increasing  rate of  bankline erosion in southern bank  and expansion of channel bars on northern banks. These hydric soils in the subgroups of aquents and aquepts are  saturated throughout year as assessed from depleted matrix with hue 10YR, 2.5Y and 5Y, chroma less than 2, stratified textures, neutral to slightly alkaline reaction, low cation exchange capacity  and poor exchangeable base status. The  assessment of land capability and soil quality  for rice production in   hydric soils  was conducted on twenty four soil mapping units derived from reconnaissance soil survey done on 1:50000 scale.  As per  land capability  assessment, these soils are  good(classII) to fairly good(IV) for arable use with limitations of low fertility status, moderate to severe wetness and moderate to rapid permeability. The soil quality rating with  multiple variable indicator transform(MVIT) technique  of  twenty hydric soil units in active and old floodplains was  medium (35 to 65per cent) with six indicators(pH, organic carbon, base saturation, effective rooting depth , structure and texture) meeting the thresh hold value  above 65 per cent.  Thirty five  per cent of total area is suitable for rice cultivation as against the current cropped area of 7.2 per cent with potassium and zinc deficiency. The determination of soil quality in relation to land capability was found useful to design best management practices for wetlands in the region that ensure sustainable land use.