The field trial was established on 19 December 2025 at an organic farm in north-eastern Sicily, Italy (Rodì Milici, Messina province) in a clay soil. The vineyard orchard, approximately 15 years old, consists of the cultivar Nero d’Avola, planted at a spacing of 2.3 × 1.0 m (4348 grape ha-1). The experiment followed a randomized complete block design with three replications. Alley crops were undersown with either barley or burr clover to establish two-layer systems, while a mixture of barley and burr clover was used to create a three-layer system. These treatments were compared with a sole vineyard system (single-layer). The same crop species were also cultivated in open-field plots to allow calculation of the land equivalent ratio (LER). Continuous measurements are planned throughout the growing season, and the first-year harvest is scheduled at the barley or burr clover flowering stage for forage production.
