Agricultural Research Management Information System

Home
Research Summary
Search
About Us
- ARMIS
- Brochure
Contact Us
Report
User Request
Data Input
Help
- Operation Manual
  - PDF
  - Video
- Program Area & Commodity
We have reached 37600 number of research entries at this moment.

- Logout

Research Detail

Home
Research
Detail

Morphological and Mineralogical Features of Some Soils from the Manpura Island in Bangladesh

A. Begum
Department of Soil, Water and Environment, University of Dhaka, Bangladesh

M. S. Hussain
Department of Soil, Water and Environment, University of Dhaka, Bangladesh

S. M. Ullah
Department of Soil, Water and Environment, University of Dhaka, Bangladesh

F. Ottner
Department of Soil, Water and Environment, University of Dhaka, Bangladesh

Abstract/ Executive Summary:

Manpura is a slender-shaped offshore is land in the lower Meghna estuary of Bangladesh comprising more than 31,000 hectares of land. It is an aggregation of many young and old islands, which in places are muddy and the materials are raw. Twenty five soil samples representing five pedons from this island were examined for their morphological and mineralogical characteristics. All these soils remain seasonally flooded for varying periods during the monsoon months when free iron and manganese a re washed down as is apparent from their grey colour. The dominant hues in these soil s vary from 2.5Y to SY. Col our varies from very dark grey to dark grey. Char Manpura, Char Mahajankandi and South Shakuchia are relatively older parts of the island and the soil profiles there appear to have developed cambic horizon. Mottles are present in different horizons of the pedons, especially in the subsoil zone. Texture of the soils of Manpura is predominantly loamy with an average content of 51% silt and 20% clay. Sand/silt ratio remains more or less constant with depth, which indicates the uniform nature of parent materials, although there are signs of stratification. The layer silicates are the dominant minerals, followed by quartz and feldspar. In the clay fractionillite is the dominant mineral occupying more than 40%. Other important clay minerals are smectite, chlorite and kaolinite. A small quantity of vermiculite is present only in two soils. With respect to clay mineralogical composition, the soils of Manpura island appear to be akin to those on the Gangetic alluvium .

Keywords: Morphology, Mineralogy, Soil, Manpura island

Location: Manpura, Noakhali district, Bangladesh.

Start Date:

End Date:

Program Area: Crop-Soil-Water Management

Commodity: Land development productivity

Objectives:

To identify the clay mineralogical and Morphological composition of Manpura island soils the Gangetic alluvium.

Methodology:

Five soil profiles were studied from the selected locations of the Manpura island. Three soil profiles were collected from paddy fields and two from plantation mangrove forest areas of about 16 years old where keora was the major species. The collected soil profiles varied in age and development. The soil sampling sites were selected in such a way that they represent the different major ecological conditions of Manpura island. Soil formation in Manpura island is still in its infancy. Most soils in the new areas can be classified as Entisols, mostly Aquents and Fluvents. Soils in the older part of the island where cambic horizon have developed may be characterized as Inceptisols, mostly Aquepts. The samples were studied by means of X-ray diffractions (XRD) using a Philips 1710 diffractometer with automatic divergent slit, 0.10 receiving slit, Cu LFF tube, 45 kV, 40mA and a single-crystal graphic monochromator. The measuring time was 1s in steps can mode and step size of 0.02°. Bulk soil samples as well as the separated clay fractions (< 2 µm) were analyzed. Sample preparation generally followed the methods described. Dispersion of clay particles and destruction of organic matter were achieved by treatment with hydrogen peroxide. Separation of clay fraction was carried out by centrifugation method. The exchange complex of each sample (< 2 µm) was saturated with Mg and K using MgCl₂ and KCl solutions by shaking. The preferential orientation of the clay minerals was obtained by suction through a porous ceramic plate. To avoid the disturbance of the orientation during drying, the samples were equilibrated during seven days over saturated NH₄N0₃ solution. After X-raying the samples, expansion tests by using ethylenglycol, glycerol and contraction tests by temperature up to 550°C were carried out. Semi quantitative estimation of minerals in the clay fraction was carried out using the corrected intensities of characteristic X-ray peaks using the method of Riedmtiller (1978). Semi quantitative mineral composition of the bulk soil samples was estimated using the method described by Schultz (1964).

Source of Information: J. Asiat. Soc. Bangladesh, Sci. 30(1): 17-28, June 2004, ISSN 1016-6947

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

Mottles are present in different horizons of the pedons, especially in the subsoil zone. Texture of the soils of Manpura is predominantly loamy with an average content of 51% silt and 20% clay. Sand/silt ratio remains more or less constant with depth, which indicates the uniform nature of parent materials, although there are signs of stratification. The layer silicates are the dominant minerals, followed by quartz and feldspar. In the clay fraction illite is the dominant mineral occupying more than 40%. Other important clay minerals are smectite, chlorite and kaolinite. A small quantity of vermiculite is present only in two soils. With respect to clay mineralogical composition, the soils of Manpura island appear to be akin to those on the Gangetic alluvium .

Knowledge Management: Journal