Effect of rice hull biochar treatment on net ecosystem carbon budget and greenhouse gas emissions in Chinese cabbage cultivation on infertile soil

Biochar, with its potential to enhance soil fertility, sequester carbon, boost crop yields and reduce greenhouse gas emissions, offers a solution. Addressing the challenges posed by climate change is crucial for food security and agriculture. However, its widespread adoption in agriculture remains in its infancy. This study assessed the effects of rice hull biochar on cabbage production and greenhouse gas emissions, especially nitrous oxide (N₂O). A trial, employing a randomized block design in triplicate was conducted from September 13 to November 23, 2022, where "Cheongomabi" cabbage was cultivated with N-P₂O₅-K₂O fertilization at 32 \(-\) $-$ 7.8 \(-\) $-$ 19.8 kg 10a⁻¹. Additional fertilizer was applied twice post-sowing. The Biochar application rates were control = 0 ton ha⁻¹, B1 = 1 ton ha⁻¹, B3 = 3 ton ha⁻¹, and B5 = 5 ton ha⁻¹. The aboveground biomass of autumn cabbage harvested 82 days after sowing was 2.40–2.70 kg plant⁻¹ in the control and biochar treatments (B1, B3, and B5), with no significant differences (p > 0.05). Cumulative CO₂ emissions during cultivation varied across treatment groups, with initial and cumulative emissions of 10.40–17.94 g m⁻² day⁻¹ and 3.63–4.43 ton ha⁻¹, respectively. N₂O emissions decreased with higher biochar application: reductions of 2.9%, 25.4%, and 41.1% in the B1, B3, and B5 treatments, respectively, compared to the control. The biochar application had no significant impact on yield but curbed soil emissions, Net ecosystem carbon balance during cabbage cultivation ranged from 0.42 to 3.41 ton ha⁻¹ for the B1, B3, and B5 treatments, respectively, compared to control. Overall, the study underscores biochar’s role in mitigating emissions and boosting soil carbon during cabbage cultivation in fall.