Soil characteristics of saline and non-saline deltas of Bangladesh

Abstract

The delta soils of Bangladesh occur in the coastal region of the Ganges tidal flood plain, the young Meghna estuarine flood plain, the old Meghna estuarine flood plain and the Chittagong coastal plains. Although delta soils constitute some of the most productive lands of the country, their characterization has received little attention, often because of limited accessibility. However, this information is necessary to maximize their use for agriculture to enhance national food security. Soil characteristics of farmers' fields from saline and non-saline delta zones were evaluated to understand their soil fertility status, salt content and distribution in these soils and their potential for the cultivation of modern rice varieties. Electrical conductivity in the saturation extract of the topsoil in the saline zone varied from 1 to 20 dS/m, whereas it ranged from 0.7 to 1.6 dS/m in the non-saline zone. The pH of these coastal soils ranged from moderately acidic to mildly alkaline (5.8-7.8) and soil organic matter varied between 1.2 and 3.6%. The tested soils had a wide range of available phosphorus (2-59 mg/kg) and exchangeable potassium varied from 0.2 cmol/kg to as high as 2.5 cmol/kg soil. Across the soils, potassium saturation was always higher than 2% of the base saturation. Soil analysis indicated widespread zinc deficiency (less than 2 ppm available Zn) in coastal delta soils. Wet-season rice is grown in most of the saline and non-saline areas and, given the moderate percolation rate of these soils and availability of good-quality river water in most of these coastal areas, the land is suitable for rice cultivation. Recently developed salt-tolerant rice varieties (BRRI dhan 40 and BRRI dhan 41 for the wet season; BRRI dhan 47 for the dry season) should be evaluated in these delta areas to replace the currently grown landraces with low productivity, and packages of proper crop and nutrient management options for these modern rice varieties need to be established. © CAB International 2010.