ABSTRACT.- Including hairy vetch (Vicia villosa Roth.) in a crop sequence before maize (Zea mays L.) can enhance the cash crop grain yield and reduce nitrogen (N) fertilizer needs, though the effects are inconsistent. This study aimed to identify the variables influencing maize grain yield response to hairy vetch as a preceding cover crop and N fertilization in maize following hairy vetch. We conducted 70 experiments evaluating four treatments resulting from the inclusion (or not) of hairy vetch previous to maize with and without subsequent N fertilization. © 2024 Elsevier B.V.