Fertilizer-Induced N2o and No Emissions in Tea Gardens and the Main Controlling Factors: A Recent Three-Decade Data Synthesis

Abstract

Tea gardens have been well documented as hotspots of nitrogen (N) oxide emissions (i.e., nitrous oxide (N2O) and nitric oxide (NO)). However, little is known about a quantitative synthetic understanding of N oxide emissions with different fertilizer regimes and the main controlling factors. Here, we performed a meta-analysis from 58 peer-reviewed publications on N oxide emissions from global tea gardens in nearly thirty years. Overall, fertilization increased N2O and NO emissions by 584% and 790%, respectively. The stimulative effect of fertilizer on N2O and NO emissions was mainly due to higher N application rates. Furthermore, compared to chemical fertilizer, organic fertilizer, combined fertilizer, biochar, and inhibitor reduced N2O emissions by 63%, 64%, 69%, and 94%, respectively. For NO emissions, only biochar amendment decreased the stimulation of fertilization by 80% (p < 0.05). Importantly, fertilization regimes, climatic conditions, and soil properties dominated fertilizer-induced N2O and NO emissions in tea gardens. On a global scale, fertilization increased mean N2O and NO emissions from global tea gardens by 44.5 Gg N yr−1 and 34.3 Gg N yr−1, respectively, wherein inhibitor amendments reduced N2O emissions by 14.0 Gg N yr−1 and biochar amendments reduced NO emissions by 4.75 Gg N yr−1. Our results suggest that in order to obtain maximum ecological and economic benefits, appropriate N fertilizer and the amendment of biochar and inhibitor should be applied for mitigation options site-specifically, and long-term, multi-area in situ experiments and microbial mechanism studies should be carried out.

Keywords: Tea gardens, Fertilization regimes, Nitrogen-oxide emissions, meta-analysis