Earthworms play an important role in the maintenance of soil ecosystem services. Their presence and activity are influenced by agricultural practices as fertilization. The objective of this research was to identify earthworm species and to quantify their abundance and biomass in a field experiment where different fertilization strategies were applied for a period of 12 years. The experiment was carried out under a semiarid Mediterranean climate, in a fallow year of a rainfed cereal system. Fertilization strategies were based on pig slurries from fattening pigs (PE) and from sows (PM) at different fresh doses distributed in six treatments: three treatments only included PE (one rate was 30 t ha−1yr−1applied at pre-sowing, and the other two treatments received 40 and 60 t ha−1yr−1applied at cereal tillering), two treatments only included PM (60 and 90 t ha−1yr−1applied at cereal tillering) and the last, it combined PE and PM (30 t ha−1yr−1of PE at pre-sowing plus 90 t ha−1 yr−1of PM at cereal tillering). Fertilization included a mineral fertilization treatment (0−FM) acting as a control.There were no variations in the abundance and biomass of earthworms registered according to the type of fertilization. Two earthworm species were identified. The endogeic species Koinodrilus roseuswas the most abundant (80%−100%). The anecic species Nicodrilus trapezoideswas notdetected in plots receiving the two highest doses of PE at cereal tillering. The absence of N. trapezoidescan be considered as a bioindicator of PE over-fertilization