Vermicompost reduces the invasiveness of the earthworm species Dichogaster bolaui compared to the use of compost in a degraded tropical soil in Northern Vietnam

• The invasive earthworm species Dichogaster bolaui is observed in erosion-damaged land in Northern Vietnam.
• D. bolaui and the millipede Asiomorpha coarctata proliferate within compost patches in fields under restoration.
• Vermicompost reduces the invasiveness of D. bolaui and the activity of A. coarctata in comparison with compost.
• D. bolaui increases soil organic matter mineralization.

In Northern Vietnam, organic fertilization programmes are being tested to restore soil fertility and reduce soil erosion. However, the amendment of organic matter in soil is also associated with the development of the invasive earthworm species Dichogaster bolaui. The objective of this study was to investigate the influence of organic matter amendment quality (compost vs. vermicompost) on D. bolaui. Our study confirmed D. bolaui development in organic patches in the field. However, we also observed that the flat-backed millipede Asiomorpha coarctata proliferated in these organic patches. Native to Asia, this millipede species is also considered as invasive in America. Both D. bolaui and A. coarctata more rapidly colonized compost than vermicompost patches. A laboratory experiment confirmed this trend and showed the limited development of D. bolaui in vermicompost. This is probably because of the decreased palatability of this substrate to soil fauna. In conclusion, any restoration practice that aims to increase the organic stocks in soils degraded by erosion should consider the quality of the organic amendment. In Northern Vietnam, vermicompost may be the preferred substrate for restoring soils while limiting the spread of D. bolaui.