Seasonal Drivers Exert Stronger Effects on Mesofauna Communities than Agricultural Management in Two Contrasting Arable Soils

Soil mesofauna play important roles in soil food webs, organic matter decomposition, and nutrient cycling. We quantified mesofauna responses to tillage, liming, fertilisation, and Geo2 biostimulant application at two Croatian experimental sites differing in soil type and land-use history: a long-term arable Stagnosol in Čačinci and a recently converted Gleysol in Križevci. Mesofauna were sampled in spring and autumn 2023 and analysed using generalised linear mixed-effects models (GLMMs). Seasonal dynamics exerted the strongest influence on mesofauna communities, with Collembola and Acari abundances approximately sixfold and sevenfold higher, respectively, in spring than in autumn. A significant Season × Location interaction for total Acari and Oribatida indicated a stronger spring increase at Križevci. Liming increased Mesostigmata (+94%) and total Acari (+33%), while recommended fertilisation increased Entomobryomorpha (+78%) and total Collembola (+46%). In contrast, tillage treatments did not significantly affect the abundance of Acari, Collembola, or their major subgroups. The Collembola:Acari ratio remained relatively stable (0.56–0.93), suggesting parallel responses of dominant taxa. Overall, site-specific conditions and seasonal variation exerted stronger effects on soil mesofauna communities than the tested management practices, emphasising the importance of local environmental factors and land-use history in shaping mesofauna community dynamics in agricultural soils.