Dual nature of soil structure: The unity of aggregates and pores

Soil is a hierarchical, self-organizing, and emergent system that supports plant and microbial growth, enables carbon sequestration, facilitates water fluxes, and provide habitat for microorganisms, all of which depend on soil structure. Recent debates have generally reduced soil functioning to geometry and topology of soil solids and pores and denied the existence and role of soil aggregates and hierarchy of solids. Here we argue that soil structure has a dual nature that essentially boils down to the interlocking of pores and solids in groupings of specific complexity and dynamics called aggregates. By comparing their architectural, chemical, and energetic parameters, we conclude that aggregates have a much…