Depth distribution of soil organic matter and burrowing activity of earthworms—mesocosm study using X-ray tomography and luminophores

Earthworms feed on organic matter present at the soil surface or within soil. Thus, its distribution in profile is likely to greatly influence earthworm behavior and, turn, their burrow system. To test this idea, two anecic and endogeic species were introduced into repacked cores (depth = 30 cm) upper half filled with a top containing 4% (0–15 lower deep 2% (15–30 cm). Earthworm was studied using X-ray tomography combined luminophores (colored particulate tracers of 63–125 ?m size) placed 0, 3, 12 cm depth, method widely used sediment ecology. We observed that earthworms had contrasting reactions conditions only burrowing more intensively part. From quantitative point view, few percent displaced. However, luminophore displacements also provided qualitative information complement tomography: (i) especially Aporrectodea caliginosa bioturbated most close (3 depth) (ii) influenced differentially Lumbricus terrestris displacing significantly luminophores, whatever initial than nocturna due intense cast activity. Beyond methodological developments, our study found zones higher contents explains why they are mainly non-tilled soils.