Ecoenzymatic and respiration-based characterization of soil microbial function in vineyard systems

Soil enzymatic and respiration profiling was applied to characterize the soil microbial functions of 20 vineyard sites across two major Slovenian wine-growing regions, Primorska and Podravje. Extracellular enzymatic activity (EEA) and multiple substrate-induced respiration (MSIR) assays were used to quantify microbial activity patterns and to link them to soil physicochemical properties, topography, and vineyard management practices. EEA and MSIR varied significantly among vineyard locations and between the two regions. Primorska sites generally exhibited higher enzymatic activity, particularly for nitrogen- and phosphorus-acquiring enzymes, and greater variability in respiration rates than Podravje. Microbial activity responded also to management practices, with higher respiration observed in organically managed soils, while enzymatic activity showed contrasting patterns with conventionally managed vineyards - exhibiting higher overall enzyme activity. However, variability among sites was high, and these trends should be interpreted within the broader environmental context. Management-, site-, and soil microbial- functional differences were translated into coherent multivariate patterns. Heatmaps, PCA, and t-SNE analyses consistently demonstrated a clear separation of samples by regional origin and additional differentiation at the microlocation level. Redundancy analysis revealed that soil chemical properties, notably pH, clay content, and total organic nitrogen, were the primary drivers of microbial function, whereas management and topography played secondary roles. These findings demonstrate that EEA and MSIR are powerful tools for assessing soil microbial functioning in vineyard soils. The observed microbial functional patterns were closely associated with environmental gradients, suggesting that these approaches provide biologically relevant information that may complement future terroir -related studies and support sustainable vineyard management.