Biochar Addition Reduces the Effect of High Nitrogen on Soil–Microbial Stoichiometric Imbalance in Abandoned Grassland on the Loess Plateau of China - Shuainan Liu; Mingjun Xie; Wende Lu; Xinyue Zhang; Mengyin Du; Yao Yao; Jianyu Yuan; Guang Li (Ecology and Evolution, 2025)