Silicate fertilizer application reduces soil greenhouse gas emissions in a Moso bamboo forest

Silicate fertilizer application in croplands is effective in mitigating soil methane (CH₄) emissions and increasing rice yield. However, the effects of silicate fertilizer on soil greenhouse gas (GHG) emissions in Moso bamboo forests, and the underlying mechanisms are poorly understood. In the present study, a two-year field experiment was conducted to investigate the effect of silicate fertilizer rates (0 (CK), 0.225 and 1.125 Mg ha^-1) on soil GHG emissions in a Moso bamboo forest. The results showed that silicate fertilizer application significantly reduced soil CO₂ and N₂O emissions, and increased soil CH₄ uptakes. Compared to the CK treatments, the cumulative soil CO₂ emission fluxes decreased by 29.6% and 32.5%, and the cumulative soil N₂O emission fluxes decrease by 41.9% and 48.3%, the CH₄ uptake fluxes increased by 13.5% and 32.4% in the 0.225 and 1.125 Mg ha^-1 treatments, respectively. The soil GHG emissions were significantly positively related to soil temperature (P < 0.05), but negatively related to soil moisture; however, this relationship was not observed between CH₄ uptake fluxes and moisture in CK treatment. Soil CO₂ emission and CH₄ uptake were significantly positively related with water-soluble organic C (WSOC) and microbial biomass C (MBC) concentrations in all treatments (P < 0.05). Soil N₂O emissions were significantly positively related to MBC, NH₄⁺-N, NO₃^--N, and microbial biomass N (MBN) concentrations in all treatments (P < 0.05), but not with WSOC concentration. Structural equation modeling showed that application of silicate fertilizer directly reduced soil GHG emission by decreasing the labile C and N pools, and indirectly by influencing the soil physicochemical properties. Our findings suggest that silicate fertilizer can be an effective tool in combatting climate change by reducing soil GHG emissions in Moso bamboo forests.