Paired nitrogen management for improving wheat yields while minimizing nitrogen losses

Excellent nitrogen (N) management techniques can improve crop yields while mitigating reactive N (Nr) losses. The synergistic effects of applying paired N management techniques have important implications for designing excellent N management strategies, but the interaction effects remain poorly known. Here, a meta-analysis was conducted to quantify the effects of optimized N management techniques (optimized N application rate, optimized topdressing, and applying enhanced-efficiency fertilizers) on wheat yield, N use efficiency (NUE), and Nr losses, as well as the interactive effects of paired N management techniques (combining an optimized N rate with topdressing or enhanced-efficiency fertilizers). The results demonstrated that an optimized N fertilizer rate reduced Nr losses by 28–31% while the wheat yield declined by 2%; however, the wheat yield increased by 2% when the reduction of N fertilizer was less than 20%. The adoption of topdressing and enhanced-efficiency fertilizers significantly increased wheat yields by 4–8% and NUE by 8–14%, while reducing Nr losses by 28–40%, and high topdressing frequency and nitrification inhibitors showed stronger positive effects on wheat yield. Paired N management techniques increased wheat yields by 3–4% and NUE by 37–38%, with additive or synergistic effects; and they also reduced Nr losses by 5–66% but showed an antagonistic effect. Such non-additive interactions amplified the positive effects on wheat production, but the benefits in terms of environmental risk reduction were weakened. Overall, this study highlights the importance of synergistic effects in innovative N management to address the trade-off between crop yield and Nr losses.