Applying woody biochar to farmland could help farmers grow healthier crops while locking more carbon into the soil, according to a new study published in Biochar. Researchers from Suncheon National University found that carefully managed applications of biochar significantly improved soil quality, crop yield, and carbon balance in red pepper fields over two growing seasons.
Biochar is a carbon-rich material made by heating plant matter under low-oxygen conditions. When added to soil, it can store carbon for long periods and enhance soil fertility. However, the ideal amount of biochar for sustaining both crop production and carbon storage has remained unclear.
To address this gap, the team tested different application levels of woody biochar, derived from conifer wood, on red pepper fields in South Korea. They applied 0, 2.5, 5, and 10 metric tons of biochar per hectare each year and measured greenhouse gas emissions, soil properties, and plant growth. They also analyzed how much carbon entered and left the system to calculate the annual net ecosystem carbon budget (NECB), a key measure of carbon sustainability.
The study found that biochar applications improved the NECB, soil structure, and organic carbon content. Fields that received higher levels of biochar produced up to 18 percent more red pepper fruit compared with untreated plots. Soils became less dense, more nutrient-rich, and better able to retain carbon. The researchers determined that optimal biochar application rates ranged from about 7 to 11 metric tons per hectare when crop residues were removed after harvest, and 2 to 7 tons per hectare when residues were returned to the soil.
"Our findings show that woody biochar can make agriculture more sustainable by improving soil health and helping to offset carbon losses," said lead author Sohee Yoon. "Using the right amount of biochar not only enhances crop productivity but also contributes to climate change mitigation."
The results provide new guidance for farmers and policymakers seeking to balance productivity with environmental stewardship. By identifying optimal biochar application levels, the study offers a practical pathway to enhance soil resilience, reduce greenhouse gas emissions, and support long-term carbon sequestration in agricultural systems.
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Journal Reference: Yoon, S., Lee, Y., An, H. et al. Sustainable woody biochar application for improving net ecosystem carbon budget, yield and soil properties in red pepper cropping systems: a two-year field study. Biochar 7, 112 (2025). https://doi.org/10.1007/s42773-025-00494-8
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About Biochar
Biochar is the first journal dedicated exclusively to biochar research, spanning agronomy, environmental science, and materials science. It publishes original studies on biochar production, processing, and applications—such as bioenergy, environmental remediation, soil enhancement, climate mitigation, water treatment, and sustainability analysis. The journal serves as an innovative and professional platform for global researchers to share advances in this rapidly expanding field.
