Short-term effect of leguminous cover crops on soil health in young vineyards with simulated global warming.

Global warming is increasingly threatening vineyards soil health, particularly in Mediterranean regions, mainly compromising their biological parameters, which are highly sensitive to rising temperatures. Sustainable management practices, such as the use of legume cover crops (CCS) have been emerging as an effective strategy to mitigate these impacts. The objective of this study was to evaluate the implementation of legume CCs in new vineyard plantations, as a sustainable soil management practice to enhance resistance and resilience to warming conditions. The experiment was conducted in Central Spain) under dry climate (Bsk, cold steppe), with an average annual temperature of 14.1 °C, and annual precipitation of 421.8 mm, 57% of which occurs between September and February and the soil presented a sandy loam texture. A completely randomised design was applied with three factors: (i) temperature: normal (current climatic conditions) vs increased (~ +1 °C) using open-top chambers (OTC); (ii) soil management with three levels: bare soil with tillage (T), and two CCs, CC Trifolium subterraneum L. (TCC), and Medicago truncatula Gaern. (MCC); and (iii) grapevine cultivar: cv.  Airén versus cv. Tempranillo. The combination generated 12 treatments with four replicates (48 experimental units). Four months after grapevine planting and CC sowing, and one month after CC mowing soil samples were collected at two depths (0–10 and 10–30 cm) to determine key soil health indicators: enzymatic activities (β-glucosidase, phosphatase, urease, N-acetyl-glucosaminidase), basal and induced respiration, pH and electrical conductivity. The infiltration rate was also determined. Results show that both MCC and TCC significantly increased β-glucosidase and urease activities in the 0–10 cm layer compared with tilled bare soil, while OTC warming reduced phosphatase and N-acetyl-glucosaminidase activities, potentially compromising nutrient recycling. The grapevine cultivar × CC interaction revealed that soils with cv. Airén responded better with Medicago truncatula Gaern, showing a significant increase in urease activity in the 10–30 cm layer, whereas in cv. Tempranillo no significant differences were observed. This suggests that the effect of CC on soil biological activity depends on the grapevine cultivar, underscoring the need to further investigate these interactions. Basal and induced respiration increased with CCs relative to bare soil but decreased under OTC warming. In addition, MCC increased electrical conductivity in the 0–10 cm layer compared to TCC and bare soil. No significant differences were observed in the infiltration rate. These findings indicate that leguminous cover crops enhance soil biological activity in the short term, while physical properties such as infiltration and chemical properties such as pH require longer periods to show significant changes. Overall, the use of leguminous CCs represents a promising strategy to sustain soil health in young vineyards under global warming, with cultivar-specific responses that warrant deeper investigation.

Acknowledgements: This study was carried out in the framework of the CUBIC project. Grants PID2023-147576OB-C21 and PID2023-147576OB-C22 funded by MICIU/AEI/10.13039/501100011033