Soil Degradation during the Period 1967-1995 in Bangladesh : I. Carbon and Nitrogen

Long-term changes in carbon and nitrogen storage in the top 100 em layers of soils from different physiographic units in Bangladesh were evaluated using 460 soil samples from 43 profiles collected in 1967 and 1994/95. The study area consisted of ten physiographic units, viz.: Old Himalayan Piedmont Plain (OHP), Tista Floodplain (TF), Barind Tract (BT), Ganges Floodplain (GF), Madhupur Tract (MT), Brahmaputra Floodplain (BF), Meghna River and Estuarine Floodplain (MF), Surma-Kushiyara Floodplain (SKF), Northern and Eastern Piedmont Plain (NEP), and Chittagong Coastal Plain (CCP). During the period 1967–1995, mean values of soil carbon and nitrogen declined by 16.2 t C ha-1 and 1.38 t N ha-1 in Bangladesh. The total carbon and nitrogen budgets showed a fall of 42.8 × 106 t C and 3.36 × 106 t N within the 27 y period in Bangladesh. All the physiographic units showed a decline in carbon and nitrogen contents except for BT which showed an increase of 3.76 t C ha-1 and 0.77 t N ha-1 for these elements....