Our previous experiment that combined three earthworm species
with three soil types showed that cast properties interactively depend
on soil types and on earthworm species (Clause et al., 2014). Casts of
anecicLumbricus terrestris had higher NH4
+and P contents than casts
of endogeic Aporrectodea caliginosa and Allolobophora chlorotica in
the Luvisol, Rendosol and Histosol soils. On the otherhand, casts of L.
terrestris had a lower C:N ratio than the two endogeic species in the
Luvisol. Casts of A. chlorotica had a higher Mg content in the
Rendosol but not in the two other soil types. These differences in
cast properties between soil types and earthworm species likely
impact the response of seeds and seedlings that germinate in casts.
Onlyone attempt has been made at assessing the respective impacts
of ingestion and cast properties (Eisenhauer et al., 2009). It showed
that seed ingestion by earthworms mostly increased seed
germination, although the effect varied with plant species, and
that earthworm casts alone—from one type of soil—primarily
decreased the germination (Eisenhauer et al., 2009).