Status of trace elements in agricultural soils of Bangladesh and relationship with soil properties

An investigation was undertaken to examine the levels of various trace elements in agricultural soils of Bangladesh and to analyze their relationship with some soil properties. Trace elements under study included Cu, Zn, Mn, As, Mo, Cd, Sb, and Pb. Forty samples of top soils were collected from farmers' fields in two major agroecological regions (AEZs) of the country. The two AEZs represented separately non-calcareous (pH around 6.5, free CaCO3 absent) and calcareous (pH around 7.6, free CaCO3 present) soils. Soil samples were digested with HF-HNO3 followed by the determination of the levels of the elements by ICP-MS. Levels of trace elements varied considerably between the locations and soil types, The clay content of the non-calcareous and the organic matter plus clay content of the calcareous soils were mainly responsible for such a variation, The total contents of all the trace elements except for As in calcareous soils were much lower than the maximum acceptable limit for agricultural soils. Generally, the concentration of each trace element in calcareous soils was considerably higher than that in non-calcareous soils. The total amount of trace elements in both non-calcareous and calcareous soils followed the order: Mn much greater than Zn>Pb, Cu>As much greater than Mo, Sb>Cd.