<b>Management solutions to handle the global-scale reactive nitrogen crisis</b>

<b>Abstract</b>The global reactive nitrogen (Nr) crisis presents a pressing challenge, requiring practices that balance Nr losses and crop productivity. Here, we evaluate the effect of 14 common management practices on Nr losses and crop productivity by reviewing 146 available meta-analyses and conduct a second-order meta-analysis based on 6382 unique primary studies comprising 20,167 paired observations. Results show that while most practices involve trade-offs or insufficient evidence, applications of enhanced-efficiency fertilizers, reduced nitrogen inputs, optimized fertilization methods, and biochar amendments consistently achieve ‘win-win’ outcomes by mitigating Nr losses (N₂O, NO, NH₃ emissions, and leaching/runoff) and improving crop productivity (nitrogen use efficiency, nitrogen uptake, and crop yield). By quantifying the average effect and go beyond qualitative information, we reveal the list of ‘win-win’ practices that facilitate global movements commensurate with reactive nitrogen crisis while trade-offs could be minimized.<b>Keywords</b>: Reactive nitrogen; Second-order meta-analysis, Nitrogen mitigation, Crop productivity, Sustainable agriculture