Fertilizer-induced N₂O and NO emissions in tea gardens and the main controlling factors: A recent three-decade data...

Tea gardens have been widely documented to be hotspots for nitrogen (N) oxide emissions (i.e., nitrous oxide (N₂O) and nitric oxide (NO)). However, a quantitative understanding of N oxide emissions related to different fertilizer regimes and the main controlling factors is lacking. Here, we performed a meta-analysis of 56 peer-reviewed publications on N oxide emissions from global tea gardens over the past three decades. Overall, fertilization increased N₂O and NO emissions (p < 0.001) by 584 % and 790 %, respectively. The stimulating effect of fertilizer on N₂O and NO emissions was mainly related to high N application rates. Furthermore, organic fertilizer treatment, combined fertilizer treatment, biochar amendment, and inhibitor amendment reduced N₂O emissions (p < 0.05) by 63 %, 64 %, 69 %, and 94 %, respectively, relative to chemical fertilizer treatment. For NO emissions, only biochar amendment decreased fertilizer-driven stimulation (by 80 %, p < 0.05). Notably, the dominant factors that influenced fertilizer-induced N₂O and NO emissions in tea gardens were fertilization regimes, climatic conditions, and soil properties. On a global scale, fertilization increased mean N₂O and NO emissions (p < 0.05) from global tea gardens by 44.5 Gg N yr^-1 and 34.3 Gg N yr^-1, respectively, whereas compared with no amendment application, inhibitors reduced N₂O emissions (p < 0.05) by 32.2 Gg N yr^-1 and biochar reduced NO emissions (p < 0.05) by 23.6 Gg N yr^-1. Our results suggest that to obtain maximum ecological and economic benefits, appropriate N fertilizer and biochar and inhibitor amendments should be applied for site-specific mitigation purposes, and long-term, multiarea, in situ experiments and microbial mechanism studies should be conducted.