Physio-graphic units:
There are 23 physio-graphic units
under 3 geomorphologic (geo-earth; morphi-form; logos-knowledge) division of
Bangladesh soil-
A. Flood Plain Areas (80% of the country)
B. Terrace Areas (80% of the country)
C. Hill Areas (12% of the
country)
A. Flood Plain Areas:
1) Old Himalayan Piedmont Plain
2) Teesta Flood Plain
3) Karatoya-Bangali Flood Plain
4) Lower Atrai Flood Plain
5) Lower Purnabhaba Flood Plain
6) Young Brahmaputra Flood Plain
7) Old Brahmaputra Flood Plain
8) Ganges River Flood Plain
9) Ganges Tidal Flood Plain
10) Gopalganj-Khulna Beels
11) Arial Beels
12) Middle Meghna Flood Plain
13) Lower Meghna River Flood Plain
14) Young Meghna Estuarine Flood Plain
15) Old Meghna Estuarine Flood Plain
16) Surma-Kushiyara Flood Plain
17) Sylet Basin
18) Northern and Eastern Piedmont Plains
19) Chittagong Coastal Plain
1) Old Himalayan Piedmont Plain
2) Teesta Flood Plain
3) Karatoya-Bangali Flood Plain
4) Lower Atrai Flood Plain
5) Lower Purnabhaba Flood Plain
6) Young Brahmaputra Flood Plain
7) Old Brahmaputra Flood Plain
8) Ganges River Flood Plain
9) Ganges Tidal Flood Plain
10) Gopalganj-Khulna Beels
11) Arial Beels
12) Middle Meghna Flood Plain
13) Lower Meghna River Flood Plain
14) Young Meghna Estuarine Flood Plain
15) Old Meghna Estuarine Flood Plain
16) Surma-Kushiyara Flood Plain
17) Sylet Basin
18) Northern and Eastern Piedmont Plains
19) Chittagong Coastal Plain
20) St.Martin’s Island
B. Terrace Areas:
21) Madhupur Tract
21) Madhupur Tract
22) Barind Tract
C. Hill Areas:
23) Northern and Eastern Hills
23) Northern and Eastern Hills
General soil type: Types emphasis on
the process of silt formation. A general soil type comprises a group of soils
which have formed in the same way and which have a broadly similar appearance.
A total of 21 general soil types have been recognized in Bangladesh. This
classification is a non-technical grouping of soil.
General Soil Types Diagnostic
Properties
A. Flood Plain Soils:-
1. Non-calcareous Alluvium Raw or
stratified alluvium present within 25 cm from surface; not calcareous or
sulphidic within 125 cm from surface.
2. Calcareous Alluvium Similar to non-calcareous alluvium but calcareous throughout or within 125 cm from surface.
3. Acid Sulphate soils Poorly or very poorly drained, grey or dark grey soils on tidal flood plains which are actually or potentially extremely acid (pH < 3.5) within 125 cm from surface.
4. Peat soil Very poorly drained soils in which organic matters (peat or muck) comprises all or more than half of the upper 80 cm.
5. Non-calcareous Grey Flood Plain soils seasonally flooded soils developed to below 25 cm, dominantly grey in sub-soils, not very strongly acidic throughout the upper 50 cm and not calcareous within 125 cm from surface.
6. Calcareous Grey Flood Plain soils Similar to non-calcareous grey flood plain but calcareous throughout or within 125 cm from surface.
7. Non-calcareous Dark Grey Flood Plain soils Seasonally flooded soils developed to below 25 cm; not very strongly acidic throughout the upper 50 cm and not calcareous within 125 cm from surface.
8. Calcareous Dark Grey Flood Plain soils similar to non-calcareous dark grey flood plain soils, but calcareous throughout or within 125 cm from surface.
9. Grey Piedmont Soil Imperfectly to poorly drained soils in piedmont alluvium developed to below 25 cm. Similar to non-calcareous grey flood plain soils but usually more prominently mottled and medium it strong acid in sub-soil.
10. Acid Basin Clays Poorly or very poorly drained heavy clay developed to below 25 cm. Very strongly or extremely acid to below 50 cm but not sulphuric or sulphidic.
11. Non-calcareous Brown Flood Plain Soils Similar to calcareous brown flood plain soils, but not calcareous within 125 cm from surface.
12. Calcareous Brown Flood Plain Soils moderately well to poorly drained flood plain soils developed to below 25 cm, prominently brown in sub-soil, calcareous throughout or within 125 cm from surface.
2. Calcareous Alluvium Similar to non-calcareous alluvium but calcareous throughout or within 125 cm from surface.
3. Acid Sulphate soils Poorly or very poorly drained, grey or dark grey soils on tidal flood plains which are actually or potentially extremely acid (pH < 3.5) within 125 cm from surface.
4. Peat soil Very poorly drained soils in which organic matters (peat or muck) comprises all or more than half of the upper 80 cm.
5. Non-calcareous Grey Flood Plain soils seasonally flooded soils developed to below 25 cm, dominantly grey in sub-soils, not very strongly acidic throughout the upper 50 cm and not calcareous within 125 cm from surface.
6. Calcareous Grey Flood Plain soils Similar to non-calcareous grey flood plain but calcareous throughout or within 125 cm from surface.
7. Non-calcareous Dark Grey Flood Plain soils Seasonally flooded soils developed to below 25 cm; not very strongly acidic throughout the upper 50 cm and not calcareous within 125 cm from surface.
8. Calcareous Dark Grey Flood Plain soils similar to non-calcareous dark grey flood plain soils, but calcareous throughout or within 125 cm from surface.
9. Grey Piedmont Soil Imperfectly to poorly drained soils in piedmont alluvium developed to below 25 cm. Similar to non-calcareous grey flood plain soils but usually more prominently mottled and medium it strong acid in sub-soil.
10. Acid Basin Clays Poorly or very poorly drained heavy clay developed to below 25 cm. Very strongly or extremely acid to below 50 cm but not sulphuric or sulphidic.
11. Non-calcareous Brown Flood Plain Soils Similar to calcareous brown flood plain soils, but not calcareous within 125 cm from surface.
12. Calcareous Brown Flood Plain Soils moderately well to poorly drained flood plain soils developed to below 25 cm, prominently brown in sub-soil, calcareous throughout or within 125 cm from surface.
13. Black Terri Soils Imperfectly to
poorly drained soils in Himalayan piedmont alluvium with a very dark brown to
black top soils >25 cm thick.
B. Hill Soils:-
14. Brown Hill Soil Excessively to
well drained hill soils, developed to below 25 cm; yellow brown to reddish
brown sub-soil; usually very strongly acid throughout 125 cm from surface.
C. Terrace Soil:-
15. Shallow Red Brown Terrace Soils Moderately well to imperfectly drained olive-yellow to strong brown soils over lying grey, Madhupur clay at 25-60 cm.
16. Deed Red Brown Terrace Soils Well drained to moderately well drained red to yellow-brown soils, overlying a strongly red-mottled substratum.
17. Brown Mottled Terrace Soils Imperfectly drained soils with a strongly mottled brown and red sub-soil, overlying a strongly red mottled substratum.
18.Shallow Grey Terrace Soils Poorly drained, grey, silty soils overlying grey Madhuput clay at 20-30 cm.
19. Deep Grey Terrace Soils Poorly drained, mainly silty soils with a grey mottled brown or red sub-soil, overlying a strongly red-mottled substratum.
20. Grey Valley Soils poorly drained, deep, grey, mainly silty soils occurring in terrace valleys.
15. Shallow Red Brown Terrace Soils Moderately well to imperfectly drained olive-yellow to strong brown soils over lying grey, Madhupur clay at 25-60 cm.
16. Deed Red Brown Terrace Soils Well drained to moderately well drained red to yellow-brown soils, overlying a strongly red-mottled substratum.
17. Brown Mottled Terrace Soils Imperfectly drained soils with a strongly mottled brown and red sub-soil, overlying a strongly red mottled substratum.
18.Shallow Grey Terrace Soils Poorly drained, grey, silty soils overlying grey Madhuput clay at 20-30 cm.
19. Deep Grey Terrace Soils Poorly drained, mainly silty soils with a grey mottled brown or red sub-soil, overlying a strongly red-mottled substratum.
20. Grey Valley Soils poorly drained, deep, grey, mainly silty soils occurring in terrace valleys.
Made Land:
21. Made Land Soils on raised
cultivation platforms; similar in color and texture to adjoining natural soils,
but better drained and often darker and browner.
1 comment:
Terrace soil is only 12% (instead of 80% as mentioned)
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