The Sequential Analysis of Iron in Main Soil Orders in Erbil City

The present study was conducted during the spring of 2024 to investigate the distribution and speciation of iron in main soil orders from various locations in the Erbil Governorate. The analysis was carried out using a sequential extraction procedure to fractionate iron into operationally defined forms: Exchangeable Fe, Carbonate Fe, Organic bound Fe, Reducible Fe, Residual Fe, Soluble Fe, Available Fe and Total Fe. Soils representing four main soil orders which included Inceptisols, Mollisols, Vertisols and Aridisols were collected from various sites including Mergasur, Choman, Shaqlawa, Rawanduz, Koya, Daraban, Harir, Grdarasha, Omermamk, Dibaga, Makhmour, and Qaraj. The results revealed significant variability in iron fractions among the locations. The residual iron form was dominant across all samples, with the highest value observed in Qaraj (85.53 mg kg-1) and the lowest in Omermamk (62.85 (mg kg-1). Exchangeable and available iron were remarkably high in Omermamk (61.00 mg kg-1 and 63.08 mg kg-1 respectively), suggesting unique geochemical conditions at that site. In contrast, most other soils contained exchangeable iron below (5 mg kg-1). Soluble iron remained generally low across the study area, with the highest value detected in Koya (5.02 mg kg-1). Overall, the findings indicate that while residual forms of iron dominate, certain areas like Omermamk exhibit unusually high levels of exchangeable iron, potentially enhancing plant iron uptake. These results contribute to a better understanding of iron dynamics in Erbil soils and support the development of site-specific soil fertility management strategies.