Land and Soil Resources Database for Grass‐Root Agricultural Development in Bangladesh S.M. Imamul Huq1 and A.F.M. Manzurul Hoque2 1Professor, Department of Soil, Water and Environment, University of Dhaka, Dhaka ‐1000,Bangladesh. 2Senior Scientific Officer, Soil Resource Development Institute, Dhaka‐1215, Bangladesh. Location of Bangladesh Bangladesh lies between 20034/ and 26038/ north latitude and 88001/ and 92041/ east longitudes. Located as an interface of two different environments - the Bay of Bengal in the south and the Himalayas in the north. Sits astride the tropic of cancer. Bordered by India in the west, north and east except for a small portion in the south-east by Myanmar. The entire south of the country is occupied by the Bay of Bengal. Physiography ¾ The three broad physiographic units belonging to three distinct geological ages: A. Tertiary hills occupying 12% area B. Pleistocene terraces covering 8% area and C. Recent floodplains spreading about 80% area of the country. ¾ These three physiographic units are again categorized into 20 different physiography considering their geomorphology and origin of soils. Climate and Agriculture ¾ Humid tropical monsoon type with three distinct meteorological seasons – summer, monsoon and winter. ¾ The rainfall ranges from 1500 mm in the northwest to 5000 mm in the northeast. ¾ The rainfall along with depth and duration of flooding is the main critical factor for agriculture in Bangladesh. ¾ The critical aspects of rainfall in relation to the use of land for agriculture is related to the uncertainty of the onset and departure of the monsoon as well as occurrence of droughts. ¾ Based on the climate, physiography and soil, Bangladesh has been divided into 30 Agro Ecological Zones (AEZ) Soils of Bangladesh ¾ Data on land and soils of Bangladesh was almost nonexistent before mid sixties. ¾The first account of the landscape and soils in Bangladesh was published in 1956 where the country was divided into seven soil tracts based on the geological origin of soils without considering the soil forming factors. Table 1. The Seven Soil Tracts of Bangladesh* No. Soil Tracts Area Sq. Km. Typical Soil (estimated) Series** 1 Madhupur Tract 10,000 Tejgaon 2 Barind Tract 13,000 Amnura 3 Tista Silt 16,000 Gangachara 4 Brahmaputra Alluvium 40,000 Ghatail 5 Gangetic Alluvium 27,000 Sara 6 Coastal Saline Tract 20,000 Barisal 7 Chittagong Hill Tract 15,000 Kaptai *Islam and Islam (1956), **SRDI (1965-1976) Soils of Bangladesh (Contd.) ¾ Rainfall is high in the north-east and gradually declines towards the west. ¾ Considering the climate as the most active pedogenic factor, Bangladesh was divided into three zones: A. Humid B. Semi-Humid and C. Feebly Arid. ¾ A pedoclimatic zone was defined as representing an aea where the climatic factor working on parent material has produced similar soils. Soils of Bangladesh (Contd.) Zone No. Name of Pedoclimatic Zone Areas and Associated Soil Types Zone 1 Humid The north-east and east submountainean hill tracts, south and south-east coastal lands. The probable soil association in the zone is a podzolic type including alluvial. Zone 2 Semi-Humid The north-notheast flat and the south- wet lowland. The probable soil association being of degraded lateritic and alluvial. Zone 3 Feebly Arid The rest of Bangladesh. The probable soil association being of a lateritic and also of a pedocalic type including alluvial. Reconnaissance Soil Survey (RSS) ¾ The information on land and soils of Bangladesh published during 1956-1957were of no significance in practical use since these were produced without much field investigation. ¾ Systematic generation of primary data regarding land and soil resources started during the early sixties by undertaking the Reconnaissance Soil Survey (RSS) program under the Soil Survey Project of the then East Pakistan with the active cooperation of FAO. ¾ The RSS was based on intensive aerial photo interpretation followed by field examination of soils made along planned traverses across the landscapes. ¾ A total of 465 soil series (taxonomic unit) were identified, described and classified particularly for the agro-service purpose through the RSS during 1965- 1976. Reconnaissance Soil Survey (RSS) ¾ Soil series were identified on the basis of differentiating characteristics such as texture, nature of the horizon developed, soil reaction, consistence etc. ¾ The physical and chemical properties of 465 soil series were determined in the laboratory and all the analytical results were subsequently published in the 33 RSS reports. ¾ Soils were mapped at the scale of 1:125000 in terms of geographical associations or complexes of soil series and phases. A total of 1034 soil associations (groups of soils that occur together within part or all of a physiographic unit or subunit) were mapped. ¾ The smallest soil series has an area of only 11 ha while the largest one has an area of 486,493 ha. The average area of a soil series is 23,989 ha. ¾ Total covered area in the RSS was 11,466,913 ha. Forest occupying 15% of the land in Bangladesh has not been covered by RSS. Contribution of RSS ¾ RSS in Bangladesh successfully filled the vacuum that existed for a long time. Through RSS people could get first hand information about the soils of Bangladesh.. Through their characterization in soil taxonomy , everybody could have some knowledge on the nature of Bangladesh soils. ¾ Some basic soil properties; morphological, physical and chemical properties of soils were made available. ¾ The information contained in the RSS reports, a comprehensive classification of Bangladesh soils was carried out by Brammer in 1971. Through this descriptive classification, the classification of the sols in Bangladesh was made understandable to the layman. ¾ The information contained in the RSS reports were utilized in making the AEZ map of Bangladesh (FAO-UNDP, 1988). ¾ Soils (taxonomic units) were classified according to two international soil classification system, -the US soil taxonomy and the FAO-UNESCO legend based on RSS data. ¾ RSS based information has been used as the baseline data to conduct the semi-detailed soil survey of the country during 1986-2001 for publishing the ‘Land and Soil Resource Utilization Guide’ for upazilas (sub-districts) of the county. General Soil Map of Bangladesh ¾ Brammer in 1971 classified the soils of Bangladesh into 20 general types based on RSS data. ¾ FAO-UNDP developed a “General Soil Map’ on the basis of Brammer’s classification at the time of making a ‘Land Resource Appraisal for Agricultural Development of Bangladesh in 1988 ¾ Later in 1997 SRDI developed another General Soil Map of the country on the basis of RSS data and further field verification General Soil Map of Bangladesh No. General Soil Type Area (ha) 1 Non -calcareous Alluvium 303180 2 Calcareous Alluvium 934513 3 Acid Sulphate Soils 458287 4 Peat 183743 5 (a-f) Grey Floodplain Soils 1417917 6 (a-b) Grey Floodplain Soils & Non-calcareous Brown 352713 Floodplain Soils 7 Mixed Grey, Dark Grey & Brown Floodplain 37641 Soils 8 Grey Floodplain & Non-calcareous Dark Grey 489668 Floodplain Soils 9a Surma-Kushiyara Floodplain Soils 302466 9b Comilla Basin Soils 16791 10 Grey Piedmont Soils 345523 11 Acid Basin Clay 471400 12 Non Calcareous Dark Grey Floodplain Soils 559470 General Soil Map of Bangladesh No. General Soil Type Area (ha) 13 Calcareous Dark Grey Floodplain Soils & 1377233 Calcareous Brown Floodplain Soils 14 Calcareous Dark Grey Floodplain Soil s with 64612 Lime Kankar 15 Non-calcareous Brown Floodplain Soils & Grey 250548 (a-b) Floodplain Soils 16 Balck Terai Soils 59652 17a Mainly Deep, Brown Soils on Low Hills, Mainly 556659 Steep Sloping 17b Deep & Shallow Brown Soils on Very Steep, High 599017 Hills 18a Madhupur Tract Soils 263607 18b Baind Tract Soils 52126 18c Akhaura Terrace Soils 10257 19a Mainly Level Terrace Soils 389037 19b Closely Dissected Terrace Soils 45734 19c Old Piedmont-plain Soils 45898 Agro Ecological Zones Based on the RSS data on land types and soils, physiography and climate, Bangladesh has been divided into 30 AEZ (FAO-UNDP, 1988) Table - 4: Area (ha) Covered by Different AEZ AEZ No AEZ Name Area(ha) 1 Old Himalayan Piedmont Plain 278361 2 Active Tista Floodplain 64488 3 Tista Meander Floodplain 657525 4 Karatoya Bangali Floodplain 172647 5 Lower Atrai Basin 57806 Lower Punabhabhava 6 Floodplain 10030 Active Brahmaputra-Jamuna 7 Floodplain 233910 Young Brahmaputra & Jamuna 8 Floodplain 401258 Agro Ecological Zones Table - 4: Area (ha) Covered by Different AEZ AEZ No AEZ Name Area(ha) 11 High Ganges River Floodplain 896031 12 Low Ganges River Floodplain 543891 13 Ganges Tidal Floodplain 1054927 14 Gopalganj Khulna Bils 154530 15 Arial Bil 9270 16 Middle Meghna River Floodplain 116705 17 Lower Meghna River Floodplain 60336 18 Young Meghna Estuarine Floodplain 367913 19 Old Meghna Estuarine Floodplain 531051 20 Eastern Surma-Kushiyara Floodplain 328324 21 Sylhet Basin 319033 22 Northern & Eastern Piedmont Floodplain 298483 Agro Ecological Zones Table - 4: Area (ha) Covered by Different AEZ AEZ No AEZ Name Area(ha) 23 Chittagong Coastal Plain 233009 24 St. Martin’s Coral Island 207 25 Level Barind Tract 347077 26 High Barind Tract 107834 27 North Eastern Barind Tract 78602 28 Madhupur Tract 287831 29 Northern & Eastern Hills 1245806 30 Akhaura Terrace 5022 9598381 Sundarban 427418 Reserve Forest 284210 Others 4446991 Total 14757000 Soil Classification (US Soil Taxonomy & FAO-Unesco Legend) ¾ Soil series identified through RSS, according to US soil taxonomy