Soybean–maize intercropping and straw returning change soil iron-associated nitrogen dynamics to increase crop yield and reduce N₂O emissions - Zhikang Li; Zhenzhen Gao; Guowei Zhang; Zihang Jiang; Hongmei Shu; Changqin Yang; Xiangbei Du; Ruixian Liu (European Journal of Agronomy, 2026)