Medicago sativa for climate-smart agriculture and soil sustainability: a review
摘要
Medicago sativa is a globally significant perennial forage legume valued for its high productivity, nutritional quality, and multifunctional role in climate-smart agriculture. This review synthesizes evidence from 130 peer-reviewed studies across 35 countries, spanning temperate, subtropical, and semi-arid agroecological zones, to (i) assess the agronomic performance and productivity of Medicago sativa, (ii) evaluate its nutritional and environmental contributions to sustainable livestock systems, and (iii) identify research and policy priorities to enhance its adoption under climate change. Quantitative data indicate dry matter yields of 12–25 t ha⁻1 yr⁻1, with higher yields in irrigated temperate systems and greater variability in rain-fed, semi-arid and tropical environments. The crude protein content ranges from 15 to 25% of dry matter, supporting high digestibility (> 70% in vitro) and efficient feed conversion in ruminants. Through symbiosis with Sinorhizobium spp., biological nitrogen fixation of 150–300 kg N ha⁻1 yr⁻1 reduces dependence on synthetic fertilizers and improves the soil fertility. Long-term studies report soil organic carbon increases of 0.3–0.8 t C ha⁻1 yr⁻1, reflecting contributions from deep roots and rhizodeposition. The deep-penetrating root enhances drought tolerance, nutrient capture, and soil structure, thereby supporting resilience in degraded and water-limited environments. Therefore, Medicago sativa enhance feed security, promotes low-emission livestock production, and contributes to climate change mitigation. Future priorities include breeding for stress tolerance, improving pest and disease management, strengthening seed and extension systems, and implementing policies to support sustainable adoption, particularly in tropical and sub-Saharan African regions.