Distribution and Geospatial Maps Based on Spatial Availability of Soil Physicochemical Characteristics at a Cyclone-affected Area in Southwestern Bangladesh

Abstract

On account of evaluating and mapping the spatial distribution of some selected physicochemical attributes of soil including the percentage of sand, silt and clay, textural class, soil reaction (pH), electrical conductivity (EC), and organic matter contents over a period of last 20 years, an investigation was carried out at cyclone-afflicted Shyamnagar sub-district, Satkhira, Bangladesh. Particle size analysis was examined by following the hydrometer method, whereas pH and EC were determined instrumentally. The carbon content of the soils was examined volumetrically by the wet-oxidation method. The amount of sand was less than the silt and clay fractions in the studied sites. Silt contents were significantly increased for over 20 years. Consequently, siltation has been taken place for the last two decades. Soil salinity was associated with the development of silt texture, altered from clay loam texture. The field moisture contents were observed to be increased (52%) which attributed to the increase of clay content with depth. Investigation revealed a very slow to moderate soil permeability class. An incremental trend (4.55% to 27.27%) of pH and EC (12.25 to 46.40 mS/cm) was noticed in the present study in contrast to the study of 1996.  Alongside, corresponding spatial variability maps of the selected chemical soil properties were plotted by applying the Inverse distance weighting (IDW) interpolation method. Results demonstrated the southern, southeastern, and southwestern corners of the study area were experienced greater clay content, alkalinity, and significant depletion of organic matter. This situation might become worsened in near future. Moreover, the adoption of several effective countermeasures should be taken in this cyclone-affected soil to alleviate the soil salinity, improve soil health, and thereby deal with a more variable climate.