Iron Dynamics and Risk of Iron Toxicity In Soils of the Forest Zone of South-Eastern Cote D'ivoire

In order to better understand the soils of the forest zone of the South-East of Côte d'Ivoire, four observation sites were identified at the Agropastorale B29 farm in the locality of Aboisso Comoé. These observations aimed in particular to quantify the different forms of iron in the soils, according to their depths and their topographical segments, in order to assess the risk of iron toxicity. For this purpose, soil pits were opened and described then soil samples were taken for laboratory analysis. The results obtained were compared to the reference values. They show that the soils are essentially Cambisols. They contain high levels of coarse manganiferric elements and clods, with polyhedral or particulate structures. They have a high concentration of free iron and total iron. Free iron is relatively more abundant in the surface horizons (0-20 cm) of the soil and in the topographic position of the lowlands. Thus, the free iron content is between 0.19% and 0.44%. A part of the free iron in the soil located on the surface of the soil where active surfaces such as clays and silts dominate, forms complexes with these particles and the other part is present in mobile forms in low topographical positions bottom. As for total iron, it is more concentrated at depth (60-120 cm), in the soils at the top and bottom of the slope with concentrations between 2.42% and 8.16%.