Forage and Seed Production of Field Bean Respond Differently to Nitrogen Fertilization and Sowing Rate

The rising demand for plant proteins and climate change highligth the need for adaptable legume crops. A three-year field experiment examined forage and seed production, as well as nitrogen (N) and phosphorus (P) accumulation in an indeterminate field bean (Vicia faba L. var. minor Beck) variety, as affected by two fertilization rates (0 and 120 kg N ha−1, i.e., N0 and N120) and two sowing rates (60 and 100 seeds m−2, i.e., S60 and S100), along with their interaction with climatic variability. Forage yield ranged from 11.1 Mg ha−1 in Year I (S100) to 6.8 Mg ha−1 in Year III (S60 and S100), and seed yield dropped from 4.1 Mg ha−1 in Year II to 1.9 Mg ha−1 in Year III, due to fewer seeds per pod and lower seed weight unaffected by fertilization and sowing rate. Nitrogen fertilization increased forage by 20% but had no effect on seed production. Field bean showed good adaptability to variable climatic conditions, compensating for lower stem number with more pods per stem. The possibility to obtain either forage or seed yield makes field bean a valuable source of plant proteins in a changing environment, contributing to the sustainability of cropping systems.