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Nowadays, when one of the most significant problems for mankind is saving the soil from pollution. It is well-known that one of the most important means of soil rehabilitation and remediation are soil inhabitants, their biodiversity and products of their life activity. Given the significant role of soil inhabitants in soil formation processes, it is important to consider their role in the processes of reprocessing and bioaccumulation of heavy metals. That especially concerns the earthworms, whose role in soil formation and maintenance of natural fertility is well-known and causes the interest of soil scientists and ecologists. The paper shows the degree of bioaccumulation of heavy metals (copper, zinc and lead) in the body of earthworms. Study involved three species of earthworms, which were collected in the vicinity of Tbilisi – Aporrectodea rosea (Savigny, 1826), Eisenia veneta (Rosa, 1886) and Allolobophora chlorotica (Savigny, 1826) – showed that earthworms of different species accumulate different amounts of heavy metals – copper, zinc and lead and, depending on the species, after being placed in heavy metals solutions, they demonstrate the different intensity of movement. The amount of heavy metals in the body of an earthworm depends on the structure of the body tissues and maybe on the structure of the skin-muscular sac.

Permanent grasslands provide a healthy and undisturbed environment. We investigated how mulching altered the soil physicochemical parameters, earthworm abundance, biomass, species composition and vegetation cover compared to grassland and cultivated alfalfa field. Microplots (2 × 2 m) were mulched with either weed control fabric (WF) alone or WF combined with straw (WF + S) on a grassland to grow tomato in Ősagárd (Nógrád county, Hungary) between 2018 and 2021. We had two other microhabitats: a conventionally cultivated alfalfa field (CA) and grassland (GR). We measured soil parameters (physical: soil moisture content (SMC), soil penetration resistance (SPR); chemical: pH, soil organic matter; and biological: earthworm abundance, biomass, species composition and vegetation). SMC was significantly higher on covered plots (WF; WF + S) compared to CA and GR. SPR values were the highest in CA and GR at 20 cm depth. The abundance and biomass of earthworms were the highest in GR and lowest in CA in all seasons. Plant abundance was highly influenced by season and habitat. Despite the higher compaction and lower SMC figures, grass vegetation still provided a more suitable environment for earthworms than mulched plots (WF, WF + S). Therefore, where there is agricultural production on grassland, we suggest leaving uncultivated and uncovered patches as biodiversity corridors.

Soil invertebrates are crucial for agroecosystem functioning yet sensitive to agricultural practices, including fertilization. Considering the postulates of circular phosphorus economy, the use of fertilizers from secondary raw materials is likely to return and increase and may even become obligatory. The effects of recycled fertilizers on soil fauna communities, however, remain poorly understood. In this paper, the effect of phosphorus fertilizer (RecF) and biofertilizer (RecB) from sewage sludge ash and dried animal (porcine) blood on earthworm’s occurrence in soil is discussed. RecB is RecF activated by phosphorus-solubilizing bacteria, Bacillus megaterium. Waste-based fertilizers were assessed in field experiments against commercial superphosphate and no P fertilization. Three levels of P doses were established (17.6, 26.4, and 35.2 kg P ha−1). Earthworms were collected after the test crop harvest (spring or winter wheat). In the experiments two earthworm species, Aporrectodea caliginosa and Aporrectodea rosea, were identified. A large proportion of juvenile individuals were recorded in 2017. The recycled fertilizers used in the experiments used in recommended doses, similarly to superphosphate, did not alter the density, biomass, species composition, and structure of earthworms. Further long-term field research is recommended.