Novel Integration of Forage Cereal-Legume Mixtures in Conservation Agriculture Enhances Weed Control and Barley Productivity in Moroccan Drylands

Abstract

Background: To our knowledge, this is the first study quantitatively investigating the mixed forage integration into dryland conservation agriculture (CA) systems in the Mediterranean region. Weed management under CA is challenging in low-input systems with limited herbicide use. Incorporating forage legumes into cereal-based systems provides a long-term solution for weed control while increasing yield. Results: Two cereal–legume combinations (triticale–pea and barley–pea) were tested at various ratios, including cereals 100%, pulses 100%, cereals 70%, pulses 30%, cereals 50%, and pulses 70%. Both mixtures significantly reduced weed pressure, increased forage dry biomass and boosted barley productivity compared to monocrops. In the triticale–pea mixtures, the 30:70 ratio produced the highest total biomass (4.58–9.03 t ha−1), outperforming the sole pea treatment. Barley yields following the 30:70, 50:50, and sole pea treatments (2.07–2.09 t ha−1) were significantly higher than those after sole triticale (1.09–1.45 t ha−1). In barley–pea combinations, the barley 70%–pea 30% ratio had the lowest weed density (57–165 plants m−2) and dry biomass (0.04–1.53 t ha−1). The barley 30%–pea 70% and barley 50%–pea 50% ratios yielded the highest forage and total dry biomass, reaching 5.59 and 10.36 t ha−1, respectively. Barley grain yields were higher after the solo pea, barley 30%–pea 70%, and barley 50%–pea 50% treatments, reaching up to 2.11 t ha−1, compared with the sole barley treatment, which yielded 1.59–1.62 t ha−1. Conclusion: These results indicate that cereal–forage legume mixtures efficiently reduce weeds while increasing forage and barley productivity under CA. They offer a sustainable alternative to traditional weed management methods.