Sensitivity of a Japanese Earthworm (Allolobophora Japonica) to Soil Acidity

Earthworms commonly dominate the soil fauna and they play important roles in terrestrial ecosystems, but their numbers decrease in acidic conditions. Their sensitivity to low pH was studied in Europe and their distributions were explained by their sensitivity. These kinds of studies have not been conducted in Japan. Sensitivity of a common Japanese earthworm, Allolobophora japonica, to acidified soils was studied. Worms withdrew its prostomium (oral organs) abruptly from Clark-Lubs buffer solutions of pH 3.9–4.1 when they were dipped into the solutions. The species did not burrow into soils of pH (H₂O) < 3.6 and died on and in the soils of pH (H₂O) < 4.0. It seemed that the species did not tolerate the soils of pH (H₂O) < 4.0. The responses to acid soil were almost same as those of European species. Soils should be maintained above pH 4 for this species.