Sustainable Intensification of Livestock Systems Using Forage Legumes

Global human population is increasing and expected to reach 9.7 billion people by 2050. Sustainable intensification (SI) of agricultural systems is key to increase food production while minimizing impact on global natural resources. Forage legumes provide a myriad of ecosystem services (ES) and represent an important tool for promoting SI in livestock systems. Forage legumes associate with soil microorganisms to reduce atmospheric N2. This N input represents a valuable contribution to increase net primary productivity with reduced C footprint. In addition, forage nutritive value generally increases, resulting in greater animal performance. When forage legumes are integrated into livestock systems, they complement the essential role of grasses by adding N to the system, improving forage quality, sharing resources with the companion grass, and enhancing soil organic matter. Soil C:N ratio is typically in a narrow range; therefore, input of N is essential to increase C sequestration and maintain the soil C:N ratio. Additional ES provided by forage legumes include enhanced efficiency of nutrient cycling, improved pollinator habitat, medicine/food for humans, timber, wildlife habitat, and shade for livestock (tree legumes). There are options of herbaceous and arboreal legumes, as well as annuals and perennials. In temperate regions, herbaceous legumes are used widely (e.g., Medicago sp, Trifolium sp.) while arboreal legumes are often found in tropical regions. There are a few options of herbaceous perennial warm-climate legumes, and some of them are still underexploited (e.g. Arachis pintoi, Arachis glabrata). Documented examples of forage legumes increasing livestock productivity are available in different regions of the world, and recent progress has been made in developing and managing forage legume germplasm adapted to biotic and abiotic stresses in tropical America, Africa, Southeast Asia, and Australia. Learning past lessons and applying the knowledge to shape the future is essential to achieve SI of livestock systems