Yes, clay soil often contains iron.
Iron's Presence in Clay Soil
Clay minerals, which are very common in soil, frequently incorporate iron into their structures. The color of the soil can even be an indicator; red clay, for example, owes its color to the presence of iron oxides. While the iron on the surfaces of clay minerals is typically oxidized and less reactive, the iron within the clay mineral structure is a significant component. This means that iron is not just a surface contaminant, but an integral part of the clay's composition in many cases.
- Red Clay: The reddish hue in many clay soils is a direct result of iron oxides. The persistence of this color suggests the iron is bound within the soil structure and not easily leached away.
- Iron Deficiency and Clay: While clay soils often contain iron, they may not always make it readily available to plants. High clay content can sometimes lead to low iron availability for plant uptake, potentially resulting in iron deficiency in plants growing in these soils. This is due to factors like low organic matter content and other soil characteristics impacting nutrient availability.
- Iron Reducing Bacteria: In some environments, bacteria can reduce iron within the clay, impacting its form and potentially its availability.
Source: As noted in a Sandia National Laboratories report, “Clay minerals are exceedingly common in soils and they often contain iron in their structures.” https://www.sandia.gov/labnews/2019/09/26/iron-switch/
