Inhibitors mitigate N₂O emissions more effectively than biochar: A global perspective

Farmlands receive large amounts of nitrogen (N) from anthropogenic activities, which increase N₂O emissions and promote crop productivity. Inhibitor or biochar applications have proven effective in reducing N₂O emissions and promoting crop yields worldwide. However, a direct comparison of the response of N₂O emissions and crop yields to inhibitor and biochar applications has not been performed. Here, we conducted a meta-analysis of 787 datasets from different locations worldwide to investigate the response of N₂O emissions and crop yields to inhibitor or biochar applications for different climate factors and experimental conditions and determine the key influencing factors. We found that inhibitor applications (37.4 %) resulted in larger N₂O emission reductions than biochar applications (20.2 %), but there was no difference in the crop yield improvement (5.8 % and 5.4 %, respectively). Nitrification inhibitor (NI) applications reduced N₂O emissions by 40.8 %, a larger reduction than that of urease inhibitor (UI) applications (24.3 %) and the combination of NI and UI applications (36.4 %); 3,4-dimethylpyrazole succinic (DMPSA) was the most effective NI in reducing N₂O emissions (50.7 %). We also found that NI applications were more effective in reducing N₂O emissions than biochar applications in different climates and experimental conditions (N source, N rate, cropland type, and soil texture). In addition, the N rate was the most important factor impacting N₂O emissions and crop yields when inhibitors were applied, whereas the experimental duration had the largest influence on N₂O emissions under biochar applications. Moreover, soil factors were also related to N₂O emissions under biochar applications or inhibitor applications. Our findings indicate that inhibitors are more effective in reducing N₂O emissions than biochar worldwide.