Vineyard physiological and productive performances after four consecutive years of cover crops inter-row and intra-row dry organic mulching

Soil management plays a key role in the sustainability of organic viticulture. While ground cover enhances soil protection, biodiversity, and nutrient cycling, it can also intensify competition for water and nutrients under Mediterranean, non-irrigated conditions. This study evaluated the medium-term effects of organic mulching on vine water status, physiology, and productivity in an organic Malvasia di Candia aromatica vineyard (Colli Piacentini, Italy). Three treatments were compared over four seasons (2020–2024): a control with alternating grass cover and tillage (C), a dry organic mulch in the inter-row (M-IR), and a mulch localized under the vine row (M-UR). Cover crops composed mainly of Hordeum vulgare, Avena strigosa, Phacelia tanatecifolia, and Trifoilum incarnatum were terminated each spring using different mechanical methods. In 2024, vine water potential, gas exchange, yield, and grape composition were assessed. Both M-IR and M-UR improved pre-dawn water potential (−0.32 and −0.31 MPa) relative to C (−0.40 MPa). M-UR showed higher photosynthesis (+14%) and transpiration (+25%), and greater yield per vine (+8%) due to larger clusters and berries. Titratable acidity was also higher in M-IR (+6%), compared to C, with no differences in sugar content. Overall, localized dry mulching enhanced vine performance and grape quality under dry, organic vineyard conditions.