Soil matrix with reddish and gray colored areas (a), soil matrix with arrows pointing to iron depletion and iron mass.

Figure 4. Examples of Fe masses. Masses in (A) occur in the soil matrix and are up to 30 mm in diameter. The gray colors are Fe depletions. In (B), an Fe mass (IM) lies in the matrix, parallel to a root channel that has an Fe depletion (ID) along it. The Fe depletion is approximately 30 mm wide.