Biochar increases 15N fertilizer retention and indigenous soil N uptake in a cotton-barley rotation system

Biochar amendments can modify fertilizer nitrogen (N) availability in soil and crop N uptake. However, how biochar addition affects crop N uptake and fertilizer N recovery under various N levels is not yet well understood. To address this question, we conducted a two-season [cotton (Gossypium hirsutum L.)-barley (Hordeum vulgare L.) rotation] pot experiment that included four N fertilizer rates (0, 75, 150, and 300 kg N ha−1, supplied as...