A two-year pot experiment was conducted to investigate the effects of the combined application of biochar and chemical fertilizer on soil quality and vegetable growth by adding different proportions of chemical fertilizer and biochar to the soil in 2022 and no fertilizer in 2023. It was concluded that the combined treatment improved the soil’s properties. After two consecutive years of planting vegetables, the improvement of soil properties was the most significant with the 1.5 g biochar + 80% chemical fertilizer optimal fertilizer application (BCF6) treatment. In comparison to the control (CK), soil pH, electrical conductivity, and dissolved organic carbon increased by 0.59 units, 166.6%, and 282.6%, respectively. Soil fertility also improved significantly, indicating that the combined treatments resulted in the slow release of nutrients to enhance the effectiveness of the fertilizers. Co-application significantly increased the yield of the edible parts of Chinese cabbage and improved its quality. The most significant effects of vitamin C content and soluble protein were observed in Chinese cabbage under BCF6 treatment, which were 3.33 and 1.42 times more than the CK, respectively. Utilizing biochar as a partial substitute for chemical fertilizers can improve soil structure and fertility over the long term while reducing the reliance on chemical fertilizers, ultimately providing sustained economic and ecological benefits for agricultural production.

Intensive nitrogen (N) fertilization in Phyllostachys edulis (Carrière) J.Houz. forests increases productivity but also accelerates nitrous oxide (N₂O) emissions, posing a challenge to balancing forest yield with environmental sustainability. Silicon (Si), a beneficial element for bamboo, has emerged as a potential regulator of soil nitrogen (N) cycling, but its role in controlling N₂O emissions in forest ecosystems is not fully understood. In this study, we conducted a factorial pot experiment using P. edulis forest soil, with data collected over two years, but only the second-year results were analyzed, with controlled N (0, 80, and 160 mg kg⁻¹) and Si (0, 25, and 50 mg kg⁻¹) additions. The experiment lasted two years, but only the second-year data were used for analysis. We investigated how Si affected soil inorganic N dynamics, enzyme activities, plant growth, and cumulative N₂O emissions. Si addition significantly reduced N-induced N₂O emissions by up to 53%, with the strongest mitigation observed under moderate N input (p < 0.05, two-way ANOVA). This effect was associated with lower activities of AMO, NaR, and NiR, together with reduced availability of oxidized N substrates, indicating that Si mitigated N₂O emissions mainly by constraining upstream N transformation processes rather than by directly suppressing N₂O fluxes. Si addition also tended to promote plant biomass accumulation. These findings suggest that integrating Si fertilization into bamboo forest management may help improve nutrient use efficiency while mitigating greenhouse gas emissions.