Influence of the management regime and phenological state of the vines on the physicochemical properties and the seasonal fluctuations of the microorganisms in a vineyard soil under semi-arid conditions

The area devoted to vineyards in the Mediterranean regions is the largest in the world, with grape production being of immense economic and social importance. After centuries of traditional vineyard management, the continuous decomposition of organic matter has degraded the soil making it difficult to ensure the desired sustainable production of wine. A medium-term field experiment was conducted to evaluate the influence of conventional tillage and no-tillage with natural vegetation managements on the physicochemical properties and microorganism populations of two vineyard soils in south-western Spain under semi-arid Mediterranean conditions. The natural vegetation management improved the soil quality compared to the conventional tillage management by increasing the soilʹs organic carbon, aggregate stability, water content, and amount and population biodiversity of culturable microorganisms (bacteria, yeasts, and moulds), while reducing the soilʹs penetration resistance. Although the total amount of soil culturable microorganisms showed seasonal fluctuations related to the weather and the phenological state of the vines, the amount of most microorganisms was mainly affected by the soil management. Only the yeast population was mainly dependent on the phenological vine state, with its amount seeming to be related to the availability of fermentable sugars from ripened grapes, and to the human activity during harvest. These results indicate that soil covered with natural vegetation may be an interesting option for the restoration of degraded vineyard soils such as are frequently found in semi-arid regions.