Depth-dependent soil mixing persists across climate zones

Significance Soil mixing occurs when sediment and organic matter are moved by biotic processes (burrowing mammals and invertebrates, root growth, and decay) and abiotic processes (movement of water and granular creep). Soil mixing plays a key role in carbon storage, nutrient and contaminant dispersion, and hillslope sediment transport, yet we lack quantitative information about soil mixing and its variation with depth in a soil profile. Here we present evidence showing that soil mixing systematically varies with depth in the soil. We also find that soils appear to be mixed similarly across climate zones, suggesting that soil mixing operates in a similar way over a range of different environments.