Resilience and Trade-Offs in a Novel Sorghum–Serradella Intercrop Under Simulated Dryland Stress Conditions

Sorghum ( Sorghum bicolor ) is a key cereal for food and forage security in arid and semi-arid regions, where climate change is intensifying drought stress and threatening sustainable crop production. Intercropping cereals with legumes is widely promoted as a nature-based solution to improve resource-use efficiency, nitrogen (N) cycling, and drylands’ resilience. We evaluated the performance and interactions of a novel sorghum–legume combination by intercropping sorghum with the drought-tolerant legume serradella ( Ornithopus sativus ) in a 10-week mesocosm experiment. Cropping systems (sorghum monocrop, serradella monocrop, and strip intercropping) were subjected to moderate or severe water stress, with or without frequent cutting. We investigated how intercropping influenced individual crop growth, N accumulation, and survival, and whether benefits at the plant level translated to the system level. Under severe water stress, sorghum maintained higher biomass and survival than serradella. Intercropping did not increase aboveground biomass or N content at the mesocosm level. However, individual sorghum plants in intercrops accumulated up to 80% more biomass and 100% more aboveground N than in monocropping. In contrast, serradella experienced reduced growth, N accumulation, and survival in intercrops. Our results reveal trade-offs in this intercrop under dryland stress, where individual crop benefits do not translate into system-level gains. Although limited to early growth and controlled conditions, the results provide valuable insights for designing resilient sorghum–legume systems, including optimizing species density, intercrop configuration, and cutting regimes in drought-prone agroecosystems.