Immediate effects of reduced tillage on soil health in a rainfed vineyard under Mediterranean conditions

Vegetation covers emerged as a sustainable alternative to tillage in Mediterranean vineyards due to their beneficial effects on soil health. However, grapevine growers remain concerned about the establishment of these covers as they may compete with vines for water and nutrients. Recent studies suggest that occasional tilling such as every other year, may mitigate some of the drawbacks associated with maintaining cover crops in Mediterranean vineyards. However, the immediate impact of such tillage operations has not been fully quantified. In this study, we evaluated the short-term impact of reduced tillage on soil health indicators in a Mediterranean rainfed vineyard that had been managed with spontaneous vegetation cover for the previous five years. Tillage led to ~25 % decrease in available water capacity in the topsoil. Organic matter content declined by 22 % while the concentrations of potassium and nitrate increased. Soil microbial biomass, basal respiration, enzyme activities, and diversity of microarthropods were significantly reduced (up to 50 %) under tillage compared to the resident vegetation treatment. Metataxonomic profiling analysis of bacterial and fungal communities revealed compositional and structural differences depending on soil management. Bacterial communities consistently exhibited higher diversity compared to fungal communities across treatments. Interestingly, the microbiome associated with bare soils appeared to be more complex and diverse compared to soils under vegetation cover. Overall, our findings demonstrated that even a short-term tillage can rapidly degrade multiple dimensions of soil health thereby underscoring the ecological value of spontaneous vegetation cover as a sustainable alternative to tillage in Mediterranean vineyards.