Landforms and soil order influence on the distribution and behavior of some soil micronutrients in several intermountain plains in southwestern Iran

The different landscape positions, the type of parent material and its formation processes, and the soil type significantly impact the distribution, behavior, and mobility of micronutrients. To investigate the effects of landscape and soil types on the distribution and behavior of micronutrient elements of iron (Fe), manganese (Mn), copper (Cu), and zinc (Zn), some genetic horizons samples were collected from sixteen representative pedons in the calcareous soils of southwestern Iran. Subsequently, the concentrations of extractable trace elements were assessed using diethylene triamine pentaacetic acid (DTPA) as well as in their total form through digestion in concentrated nitric acid. The results showed that the change range in the available form of studied micronutrients varied between 2.5 to 31.2, 0.3 to 3, 2.1 to 60.2, and 0 to 3.8 mg kg-1 for Fe, Cu, Mn, and Zn respectively. The examination of the chemical forms of micronutrients in both surface and subsurface samples unveiled that the majority of the investigated chemical forms exhibited higher quantitative levels in the surface samples compared to the subsurface samples. v(%CaCO3) of the soil increased when the soil moisture regime largely depends on the percentage of organic carbon (% OC) content, soil texture, and type and content of clay minerals. The highest amounts of available micronutrient elements were found in Mollisols and Alfisols soil orders. Additionally, the highest available form of Cu, Zn, and Fe were found in lowland soil units (LL), while Mn was detected in piedmont plains (PP) landform. Consequently, it can be inferred that the cycling of micronutrients is influenced by varying levels of soil development, which in turn impact the properties of the soil.