Impact of land use dynamics on soil organic carbon in the agricultural soils of Bangladesh

In Bangladesh, high population pressure (more than 160 million) has forced the production of two, three or more crops a year on the same land, resulting in a very short fallow period. This short fallow period leaves little or no time for the land to regain all its natural attributes, which are essential for its biophysical conditions. Such intensive land use could cause widespread land degradation due to loss of soil organic carbon (SOC) and its associated effects of nutrient mining. Considering the above, 190 soil samples were collected from the Brahmaputra and the Ganges alluviums by revisiting the sites sampled previously (1989-92) to quantify the SOC loss or gain. SOC datasets of current soil samples (2012) and the historic data sets (1989-92) revealed that SOC declined across the study sites as well as across the alluviums. Loss of SOC is significant in the highlands (HL) and medium highlands (MHL) sites but its loss is insignificant in the medium lowland (MLL) and lowland (LL) sites. The reason for such losses of SOC in the HL and MHL sites are at least partly due to intensive cropping with little addition of crop residues and even improper management. So, policies based on recommended management practices (RMPs) should be formulated for SOC sink and sequestration in the alluvial soils of Bangladesh

Soil organic carbon dynamics in the agricultural soils of Bangladesh following more than 20 years of land use intensification

Soil organic carbon (SOC) is a key soil quality indicator, as it is a source and storage of plant nutrients and plays a vital role in soil fertility and productivity maintenance. Intensification of agriculture is known to cause SOC decline; however, much of the evidence stems from field-scale experimental trials. The primary aim of this study is to investigate how more than 20 years of agricultural land use intensification in Bangladesh has influenced SOC levels at landscape levels. This was achieved by revisiting in 2012 four sub-sites from the Brahmaputra and Ganges alluviums which were previously sampled (1989–92) by the Soil Resource Development Institute and collecting 190 new samples. These were located at different elevations and subjected to differing amounts of inundation. The SOC was determined using the same method, potassium dichromate wet oxidation, used in the 1989-92 campaign. A comparison of the SOC in the 2012 samples with their historic levels (1989–92) revealed that overall SOC declined significantly across both alluviums as well at their four sub-sites. Further analysis, however, showed that SOC has declined more at higher sites. The higher sites are inundated to a limited level, which makes them suitable for growing multiple crops. Among the land types considered here, the low land sites (because of their topographical position) remain inundated for a greater part of the year, allowing a maximum of only one crop of submerged rice. As a result of reduced biomass decomposition due to anaerobic conditions when inundated, and lower land use/cropping intensity, SOC accretion has occurred in the lower land sites. The SOC levels in South Asian countries are inherently low and agricultural land use intensification fuelled by growing food production demand is causing further SOC loss, which has the potential to jeopardise food security and increase the environmental impact of agriculture

Article Retracted: Estimation of soil carbon stock in some wetlands of the northeastern region of Bangladesh

This article has been retracted due to authorship dispute among original authors