Ground Cover Management Drives Functional Trajectory and Microbial Efficiency in a ‘Koroneiki’ Olive Orchard

Abstract Purpose: This study aimed to evaluate the impact of different ground cover management practices (Cover crop, Mowing, and Herbicide) on the microbiological and physical-hydric soil attributes of a young ‘Koroneiki’ olive orchard under subtropical conditions in Southern Brazil. Methods: The experiment was conducted between 2022 and 2024. Soil samples were collected annually at depths of 0–10 and 10–20 cm during autumn and spring. The variables analyzed included microbial biomass carbon (MBC), soil basal respiration (BSR), metabolic quotient (qCO 2 ), enzymatic activities (FDA and Urease), and water-holding capacity. Data were submitted to factorial ANOVA, Pearson correlation, and Principal Component Analysis (PCA) to identify integrated functional patterns. Results: Temporal factors (Year and Season) were the primary sources of variation in soil attributes. Individual management practices did not significantly alter most soil health indicators in the univariate analysis. However, exploratory PCA suggested an emerging functional trajectory by the third year. In this multivariate space, Cover crop management occupied a central, balanced position, while Herbicide application exhibited a subtle spatial shift toward the nitrogen-cycling (urease) vector. This overall pattern, alongside independent temporal observations of ecophysiological stress (qCO 2 ), supports the hypothesis of a functional “time lag”, suggesting that early management-induced shifts may occur before structural carbon stocks detectably change. Conclusion: Conservationist ground cover management, particularly the use of multi-species cover crops, shows potential to direct young olive orchards toward a trajectory of biological stability. Furthermore, multivariate approaches offer valuable exploratory insights into early soil health dynamics during the critical orchard establishment phase.