Anecic earthworms (Lumbricus terrestris) facilitate the burial of surface-applied wood ash

Abstract

The purpose of our study was to determine whether earthworms facilitate the burial of surface-applied wood ash. We mixed a fluorescent tracer powder with fly ash from a commercial biomass boiler to track and quantify ash burial in microcosms containing different densities of the deep-burrowing anecic earthworm Lumbricus terrestris L. While passive incorporation of the wood ash-tracer mix from the surface in the absence of earthworms was limited (rarely penetrating more than 2 cm below the surface), earthworms increased the amount of ash-tracer found belowground and the maximum depths at which ash-tracer was observed (up to 16 cm deep). We suspect that earthworms facilitated wood ash burial primarily by creating burrows down which wood ash could be carried by water and by burying wood ash-covered leaf litter. Earthworms may help increase the efficacy of wood ash amendment in ecosystems where it is impractical to manually mix amendments into the soil (e.g. forests).