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FIG. 8. Modeling of the interactions between roots and soil structure. (A) Comparison between two 100-d-old maize (Zea mays L.) root systems, the first one (left-hand side) grown in a homogeneous soil volume and the second (right-hand side) grown in a structured soil consisting of a 25-cm-thick tilled layer with distributed dense clods, a 3-cm plow layer and a 
1.2-m-deep subsoil with biopores (earthworm burrows). In the case of the structured soil, the interactions between growing roots and soil structure have led to reduced rooting depth and lateral expansion of the root system. This is largely due to the trapping of roots in macropores at certain soil depths (50–55 cm in particular), as shown by (B) the high occurrence of root-to-macropore distances less than the voxel size (1 cm) .
