Biochar in Compost

Explore the benefits of incorporating biochar into composting processes. Understand its impact on soil health, crop yields, and environmental sustainability. Dive into case studies from Rexius and Pacific Biochar, and learn application tips for farming.

US Biochar Initiative
Nebraska Forest Service
Subscribe to newsletter
By subscribing you agree to with our Privacy Policy.
Thank you! Your submission has been received!
Oops! Something went wrong while submitting the form.
Download Files

Biochar in Composting: A Quick Guide for Professionals

What is Biochar and Why Use It in Composting?

Biochar is a carbon-rich product made from biomass like leaves, wood chips, and agricultural residues. When added to compost, biochar can:

  • Boost the activity of composting microorganisms, speeding up the composting process.
  • Produce a compost comparable to mineral fertilizers but with a lower environmental impact.
  • Improve soil health and increase crop yields when added to soil.

How to Use Biochar in Composting?

  • Incorporate biochar just like any other composting ingredient.
  • Ideal biochar-to-compost ratio: 5% to 10% by volume. Avoid going beyond 20-30%; it can hamper biodegradation.

Benefits of Using Biochar in Composting

Economic Benefits

  • Faster composting process, reducing processing time.
  • Cost savings from less frequent pile turning, reducing labor and fuel expenses.
  • Higher nitrogen content, offering a better nutrient profile than regular compost.

Environmental and Non-economic Benefits

  • Offers a solution to biomass waste that would otherwise end up in landfills.
  • Biochar feedstocks are natural and renewable.
  • Transforms low-value waste into a product that can enhance soils.

Case Studies

Rexius, Oregon

  1. Experimented with two compost piles: one with biochar and one without.
  2. Found the biochar-compost had more moisture, nutrients, and better quality.
  3. Using biochar resulted in higher nutrient values, more beneficial bacteria, labor savings, and a more valuable end product.

Pacific Biochar, California

  1. Collaborated with the Oasis Vineyard to improve soil health and water conservation.
  2. Discovered that biochar-compost treatments increased harvest yields by 45% and enhanced soil water use efficiency.

Using Biochar-Compost in Farming

  • Biochar-compost can be applied using regular compost spreaders.
  • The specific amount needed depends on several factors. Check the Biochar Atlas or the Biochar Selector tool for guidance.


Improving your soil can lead to a more productive garden or farm. While biochar might be more costly upfront, the potential yield increases and environmental benefits make it a worthy investment.

For more details

Visit the Biochar Atlas at

Adding biochar activates the composting process by enhancing the activity of microorganisms, which raises the temperature, reduces composting time, and speeds up stabilization of the compost.1 The use of biochar during the compost process yields a product comparable to those obtained with mineral fertilizer additions with a lower environmental impact.2 More recently, researchers found that benefits of co-composting with biochar far outweighed any drawbacks or side-effects when compared with other amendments. The quality of biochar-compost improves soil health and can boost crop yields.3 To use biochar in the composting process, the material should be added just like any other composting ingredient using existing equipment. The scientific literature and experience of composters indicate that the best ratio of biochar to compost is in the range of 5% to 10% by volume. Adding more than 20% or 30% is not recommended as an excessive amount can interfere with biodegradation.4


Increased production and savings: Composters who use biochar often see processing time reduced. More importantly, they report cost savings from turning piles less frequently. The fuel and labor savings are even more appealing than reducing compost time.

Higher quality material: Increased nitrogen in the final product gives biochar-compost a better nutrient profile than compost alone, making it a better soil amendment.

Interested in learning more about the economics of biochar? See the Biochar Atlas-Cost Benefit Analysis tool, which guides users to assess whether biochar is a good investment for your soil.

Non-economic benefits

Biochar is made from a variety of biogenic biomass sources (leaves, wood chips, agricultural residues, orchard pruning, vineyard cuttings, and many others). As a biogenic resource, biochar feedstocks are natural and renewable. Many locations across the United States have excess biomass with little or no market value. These materials are often either burned or sent to a landfill. Compost companies provide a valuable mechanism to divert large-scale waste biomass resources and make them into something that can help improve soils. Biochar is a new product made from low-value material that can help add value to compost. In so many communities, excess biomass shows up at landfills for disposal. Every fall, when the leaves drop, the level of waste biomass that gets sent to the landfill is disturbing. This is also true for the debris from a strong windstorm or ice storm event. If we can develop new markets for low-value biomass (like biochar), we are helping to create natural, renewable, locally produced material that can benefit people and the environment.


CHALLENGE/OPPORTUNITY: Jack Hoeck, VP of Environmental Services at Rexius, a family-owned compost and soil producer in Oregon, heard about the benefits of biochar through conversations with John Miedema of BioLogical Carbon. He was intrigued by the material as a possible new amendment to help the company produce better compost.

SOLUTION/APPROACH: Rexius started by creating two compost windrows, one with biochar and one without. In the windrow with 5% biochar by volume added, the compost-biochar had more moisture, nitrates, and other nutrients than the pile without biochar. Overall, the quality was better in the biochar windrow.

RESULTS: Since using biochar in the compost process, Rexius has continued to record higher nutrient values in their biochar-compost than compost without biochar. They also report higher beneficial plant bacteria and microbes compared to compost without biochar. Higher nutrients and more beneficial microbes create a higher value soil product that commands a better price for their gardening products. Jordan Launch of Rexius mentioned there are multiple benefits from incorporating biochar in their composting process, including labor and fuel savings from not having to turn the compost pile as often. This, along with a higher value end product, makes investing in biochar well worth it.

CONCLUSION: "The better your soil, the more productive your garden will be (whether that is better tomatoes, more colorful and vibrant flowers, or higher yields of lettuce or kale). Biochar and biochar-compost help improve soil. Though the material costs more, it results in greater yields and makes it well worth the investment."


CHALLENGE/OPPORTUNITY: Oasis Vineyard in King City, CA, was interested in trying different amendments to study how biochar and compost treatments affect soil water use, soil health, vine growth, harvest yields, and grape quality. The vineyard had soils with low organic matter and needed to conserve more water.

SOLUTION/APPROACH: Starting in 2016, the Sonoma Ecology Center, UC Riverside, and Pacific Biochar worked with the Oasis Vineyard manager Monterey Pacific Inc. to develop a multi-year field trial with funding from the California Department of Water Resources. Treatments included biochar only, compost only, biochar-compost, and a control (no amendment).

RESULTS: Some findings include:

  • The highest yield came from the biochar-compost treatment resulting in a 45% increase over the control.
  • Increased pruning weight was observed for both the compost and the compost + biochar treatment.
  • Higher cluster counts were observed for both the biochar and the compost + biochar treatments.
  • All treatments received the same irrigation regimen throughout the trial, demonstrating improved water use efficiency where soil had been amended.

CONCLUSION: Biochar and compost treatments can improve water use efficiency, vine growth, harvest yields, and soil health for vineyards planted on low organic matter sandy soil. The vineyard manager, Monterey Pacific, said the return on investment for adding biochar paid off in the first grape harvest with higher profit expected over the life of the vines.

Tips for using biochar

Biochar compost products can be spread using the same type of equipment farmers use to spread compost. It can either be worked into the soil using a plow or side-casting along rows, as in the case of biochar-compost vineyard applications. The amount of biochar-compost you should apply to your soil will depend on various factors. To learn more about how biochar can help your soil, view the Biochar Atlas at The Biochar Selector tool can guide you on the amount of biochar for your soil:

Reference Guide

  1. M.A. Sanchez-Monederoa, M.L. Cayuelaa, A. Roiga, K. Jindob, C. Mondinic, N. Boland. 2018. Role of biochar as an additive in organic waste composting. Bioresource Technology. 247(1154-1164).
  2. Gang, D.R., Collins, D., Jobson, T.B., Seefeldt, S., Berim, A., Stacey, N., Khosravi, N., & Hoashi-Erhardt, W. (2019). Integrating Compost and Biochar for Improved Air Quality, Crop Yield, and Soil Health.
  3. João A. Antonangelo, Xiao Sun, Hailin Zhang. 2021. The roles of co-composted biochar (COMBI) in improving soil quality, crop productivity, and toxic metal amelioration. Journal of Environmental Management
  4. Camps, M. and T. Tomlinson. 2015. The Use of Biochar in Compost. International Biochar Inititiative.
  5. Sánchez-García, M., Albuquerque, J.A., Sánchez-Monedero, M.A., Roig, A., Cayuela, M.L., 2015. Biochar accelerates organic matter degradation and enhances N mineralization during composting of poultry manure without a relevant impact on gas emissions. Bioresource Technology. 192, 272–279.
  6. M.L., 2015. Biochar accelerates organic matter degradation and enhances N mineralization during composting of poultry manure without a relevant impact on gas emissions. Bioresource Technology. 192, 272–279.
  7. Advancing Organics Management in Washington State: The Waste to Fuels Technology Partnership 2019-2021 Biennium. 2022. Washington State Department of Ecology. Publication 22-07-002.
  8. Pacific Biochar. 2021.

This presentation was partially funded by the National Fish and Wildlife Foundation Innovative Nutrient and Sediment Reduction Grant Program.

Disclaimer: The views and conclusions contained in this video are those of the authors and should not be interpreted as representing the opinions or policies of the I.S. Government or the National Fish and Wildlife Foundation and its funding sources. Mention of trade names or commercial products does not constitute their endorsement by the U.S. Government, or the National Fish and Wildlife Foundations or its funding sources.

Statement: This material is based on work supported by the U.S. Environmental Protection Agency (Assistance Agreement No. CB96358201) and the National Fish and Wildlife Foundation’s Chesapeake Bay Stewardship Fund, which promotes community-based efforts to develop conservation strategies to protect and restore the diverse natural resources of the Chesapeake Bay.