Crop rotations reshape the fate of residual and current fertilizer nitrogen: A consecutive 15N tracing study in flax-based systems on the Loess Plateau - Haidi Wang; Xingkang Ma; Bin Yan; Yuhong Gao; Zhengjun Cui; Bing Wu; Yifan Wang; Jing Han; Mingli Wan (Field Crops Research, 2026)