Nanozeolite-coupled biochar-based phosphorus fertilizer decreases soil N₂O emissions in a subtropical Moso bamboo...

A novel nanozeolite-coupled biochar-based phosphorus fertilizer (NBP) exhibited a significant potential for enhancing P-utilization efficiency and plant growth. However, impact of these nanofertilizers on soil N₂O emissions and the underlying processes have not been fully elucidated within subtropical forest ecosystems. Here, the effects of varying NBP application rates (0, 450, 900 and 1350 kg ha^-1) on soil characteristics and N₂O effluxes in a subtropical Moso bamboo forest over 12 months were investigated. Results indicated that increasing NBP dose decreased annual cumulative soil N₂O emissions by up to 20 %. The NBP additions did not change soil temperature, and N₂O effluxes did not correlate with soil moisture. However, NBP amendment significantly enhanced the concentration of water-soluble organic C (WSOC) while decreasing NH₄⁺-N, NO₃^--N and water-soluble organic N (WSON) pool sizes. Furthermore, NBP amendment lowered the activities of N-cycling enzymes, including urease, protease and nitrite reductase. Across all treatments, soil N₂O efflux exhibited positive correlations (P < 0.01) with the levels of NH₄⁺-N, NO₃^--N, WSON, WSOC and microbial biomass C, along with the urease, protease, and nitrite reductase activities. Structural equation modeling revealed that the reduction in N₂O emissions following NBP application was primarily driven by decreases in NH₄⁺-N and NO₃^--N concentrations and the activities of N-cycling enzymes. These findings demonstrated that NBP effectively mitigated soil N₂O effluxes in subtropical bamboo forests by reducing pool sizes of labile N and suppressing activities of enzymes regarding N-cycling. These findings highlight NBP's potential to reduce N₂O emissions in subtropical forests, supporting climate change mitigation strategies and sustainable soil management.