Legume pre‐crops can improve following cereal yields and reduce climate impact

Legumes are increasingly promoted as a diversification strategy to mitigate externalities in low‐diverse cropping systems. Their inclusion can enhance agronomic performance of subsequent crops and reduce external inputs, potentially improving sustainability of current agricultural systems. This study aimed to (i) compare the pre‐crop effect of legumes and cereals on the yield and quality of a following cereal crop and (ii) assess the environmental impact of rotations with and without legumes. Field trials were conducted between 2023 and 2025, under conventional and organic management practices, to compare legumes (spring faba bean [ Vicia faba L.], spring pea [ Pisum sativum L.], and kidney bean [ Phaseolus vulgaris L.]) with cereals (spring wheat [ Triticum aestivum L.], spring barley [ Hordeum vulgare L.], and spring durum wheat [ Triticum durum D.]) as pre‐crops to spring barley, spring wheat, and winter barley. Cereal yields significantly increased after legume pre‐crops under conventional management, with increases of 17%–34% in 2024 and 24%–54% in 2025. At the same time, total nitrogen uptake by the following crop was higher, even when fertilizer inputs were reduced. No pre‐crop effects were observed under organic management. Life cycle assessment showed a 9%–42% reduction in climate impact per hectare over the 2‐year rotation and an 11%–38% reduction per kilogram product when introducing legumes in cereal‐based rotations under conventional management, while no such effect was present in organic conditions. Further research into underlying agronomic and ecological mechanisms is needed to better understand legume pre‐crop effects and their effects on the sustainability of rotation systems.