Seasonal Dynamics of Earthworm and Microarthropod Communities in rural Home Garden agroecosystems: Linking Soil Properties to Biological Soil Quality

Soil invertebrates like earthworms and soil microarthropods are key players in the soil ecosystem by maintaining soil structure, nutrient cycling, and biological fertility in home‑garden agroecosystems. Even though short-term studies exist on these individual groups and their role in soil ecosystem functioning, long-term data from non-polluted reference sites are very scarce. This study was carried out in twenty-five home garden agroecosystems (two seasonal samplings per year for five years) from a non‑polluted area (home gardens with no soil pollution and no input of chemical pesticides/insecticides or chemical manures) to evaluate temporal patterns of soil fauna and their relationships with soil physicochemical properties. Soil cores (10 x 10 x 10 cm) were collected from the home gardens in triplicate for microarthropod estimation, and earthworms were collected from the home gardens using the mustard water extraction method. Earthworm abundance, total microarthropod abundance, and QBS‑ar scores were assessed along with soil temperature, pH, moisture, organic carbon, and electrical conductivity in each home garden. The total earthworm abundance showed clear seasonal dynamics and inter‑annual variability, with higher densities generally associated with cooler, moister seasons and soils richer in organic carbon. Microarthropod abundance and QBS‑ar scores also varied significantly among seasons and gardens and were moderately correlated with soil organic carbon and moisture, indicating a consistent link between soil biological and physicochemical soil quality. Mixed‑effects modelling and multivariate ordination revealed that home garden age, season, and soil moisture were the main drivers of faunal abundance, while pH and EC exerted secondary but detectable effects. Together, these findings show that combined monitoring of earthworm abundance, microarthropod abundance, QBS‑ar scores, and soil properties provides a robust, taxonomically simple framework for assessing soil quality and temporal stability in non‑polluted tropical home gardens and offers a valuable reference for comparison with contaminated urban and industrial soils.