Influence of Soil Organic Matter Content on Abundance and Biomass of Earthworm (Oligochaeta: Lumbricidae) Populations

The current study explores the influence of soil organic matter content on abundance and biomass of earthworm communities. The observation was carried out on three type of soils: Pellic Vertisols (very fine texture), Cromi-Vertic Luvisols (fine texture) and Calcaric Fluvisols (medium texture) from the Balkan Peninsula (Bulgaria). The field experiment was provided on uncultivated plots. In the studied area earthworm fauna comprises of four species: Aporrectodea rosea, Aporrectodea caliginosa, Lumbricus terrestris and Octolasion lacteum. We found peregrine lumbricid taxa, which are widely distributed in European soils. Our study demonstrated that soil organic matter has a positive effect on lumbricid populations. It was revealed that augmentation of soil organic matter favours characteristics of earthworm communities. The soil organic matter content and earthworm abundance are in strong positive correlation (r > 0.981). The same relationship was revealed between the biomass of lumbricid fauna and amount of soil organic matter (r > 0.987). In sum, the soil organic matter could be used as an indicator for earthworm communities in uncultivated soils.