Durum wheat-vetch intercropping in Mediterranean agroecological systems: Effects on yield, nitrogen balance, and farm profitability

Abstract

Cereal–legume intercropping offers a viable pathway for advancing the agroecological transition of Mediterranean farming systems from conventional monocultures to more diversified and sustainable agroecosystems. However, field-based evaluations, particularly involving underutilized species and contrasting input levels, remain limited. This study assessed the performance of a low-input intercropping system combining durum wheat and common vetch (Vicia sativa L.), compared to fertilized and unfertilized sole crops, over two growing seasons (2022–2024) in Southern Italy. Compared to the input-intensive monoculture, the intercropping system matched or exceeded grain yield in 2022–2023 (3.31 vs. 3.03 t ha⁻¹) and was comparable in 2023–2024 (2.67 vs. 2.79 t ha⁻¹), despite a sharp decline in rainfall (314.6 mm vs. 673.6 mm) and a rise in mean temperature (15.47 °C vs. 13.58 °C), which increased drought stress. Protein content was comparable or higher (13.9 % vs. 12.3 % in 2022–2023; 12.4 % vs. 12.3 % in 2023–2024), and nitrogen uptake increased by 15.2 kg ha⁻¹ (91.3 vs. 76.1 kg ha⁻¹) in 2022–2023 and 11.9 kg ha⁻¹ in 2023–2024 (66.6 vs. 54.7 kg ha⁻¹). Common vetch demonstrated the highest nitrogen accumulation and contributed up to 124.6 kg N ha⁻¹ via crop residues, enhancing nutrient cycling. Land Equivalent Ratios (1.62 and 1.35) confirmed superior land-use efficiency. Economically, intercropping achieved the highest contribution margin (€280.6 ha⁻¹), outperforming the fertilized wheat monoculture (€47.5 ha⁻¹), despite additional seed separation costs. While absolute performance declined under drought, intercropping remained competitive or superior to monocultures across all metrics, reinforcing its potential as a resilient, low-input solution for Mediterranean agriculture. Further research, supported by long-term field trials, should aim to validate these benefits, improve legume drought tolerance, and refine species combinations to enhance resilience and adaptability in dry Mediterranean environments.