Because each fixes real limits of the other.

What the evidence shows?

Scientific literature is consistent. When biochar is added during composting, both processing and agronomic outcomes improve.

An October 2025 peer-reviewed paper shows that, at roughly a 10 percent inclusion rate, co-composting with biochar:

• Reduces nitrogen losses and ammonium emissions
• Lowers heavy metal bioavailability
• Improves aeration and organic matter breakdown
• Increases microbial activity and humic compounds

Downstream, plants show higher nitrogen and phosphorus uptake and higher biomass yields due to improved nutrient availability.

What happens in practice?

Real-world data confirms the lab results. Earth Foundries, Inc. documented composting in a covered aerated static pile system with 10 percent biochar. Results included:

• Lower VOC emissions
• Faster curing to compost maturity
• Higher NPK in finished compost
• Lower salinity

Why this matters for composters?

Biochar is not only a soil amendment. It is a process tool.

Co-composting with biochar helps operators:

• Stabilize nitrogen
• Improve pile structure and airflow
• Reduce odor and emissions risk
• Shorten processing time

Important caveats

This is not automatic.

• Ten percent is a reference point, not a rule
• Biochar quality matters
• Emissions gains depend on good compost management
• Economics remain site-specific

So, the right question is not “Should I add biochar? It is “Where does biochar remove risk or bottlenecks in my operation?”

Original article published on Linkedin byTera Lewandowski, Director of Agricultural Markets, from the United States Biochar Initiative (USBI)