Abstract
Nitrous oxide (N2O) is a major greenhouse gas (GHG) responsible for global warming. Improper fertilization in agricultural fields, particularly excessive nitrogen (N) application, accelerates soil N2O emissions. Though partial substitution with organic fertilizer has been implemented to mitigate these emissions, the effect on perennial systems, such as tea plantations, remains largely unexplored. Therefore, the present study monitored soil N2O emissions for a year in a tea plantation in South China under the following treatments: no N fertilizer (control, CK), chemical fertilizer alone (CF), replacing 40% of chemical fertilizer with organic fertilizer (CF + OF), and organic fertilizer alone (OF). Our results showed that the annual cumulative N2O emissions from the plantation soil ranged from 1.03 to 3.43 kg N2O-N ha−1. The cumulative N2O emissions, the yield-scaled N2O emissions (YSNE), and the N2O-N emission factor (EF) from the soil were the highest under the CF + OF treatment but the lowest under the OF treatment. Further analysis revealed that fertilization, mainly chemical fertilization, increased the soil ammonium (NH4+-N) and nitrate (NO3−-N) levels by 182–387% and 195–258%, respectively, and tea yields by 120–170%. However, tea yield decreased gradually with increasing organic substitution. These results prove that complete organic substitution reduces soil N2O emissions and tea yield and suggest adopting an appropriate substitution rate for optimal effect. Further random forest (RF) modeling identified water-filled pore space (WFPS; 20.27% of total variation), soil temperature (Tsoil; 19.29%), and NH4+-N (18.27%) as the key factors significantly contributing to the changes in soil N2O flux. These findings provide a theoretical foundation for optimizing fertilization regimes for sustainable tea production and soil N2O mitigation.
Published Version
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