A new review highlights how bone char made from animal bones could play an important role in sustainable agriculture by recycling phosphorus, improving soil health, and reducing environmental pollution.
The study, published in the journal Biochar , examines how bone char produced through the pyrolysis of animal bones could help transform a large global waste stream into a valuable agricultural resource. Researchers estimate that worldwide slaughterhouse activities generate between 95 and 126 million tonnes of animal bone waste each year.
Rather than being discarded or incinerated, these bones can be converted into bone char, a porous carbon rich material that contains high concentrations of phosphorus, calcium, and magnesium. When applied to soils, bone char can act as a slow release fertilizer, helping crops access nutrients more efficiently while reducing nutrient losses to the environment.
“Bone char represents a promising example of circular resource management,” said the study’s lead author. “By transforming animal by products into a valuable soil amendment, we can recycle nutrients that would otherwise be lost and support more sustainable agricultural systems.”
Phosphorus is an essential nutrient for plant growth, but it is also a finite resource that is primarily obtained from mined phosphate rock. At the same time, large amounts of phosphorus are lost from agricultural soils through runoff, erosion, and leaching, contributing to water pollution and eutrophication.
The researchers estimate that converting global bone waste into bone char could theoretically replace between 13 and 32 percent of the global phosphorus fertilizer market. Such a shift could reduce reliance on nonrenewable phosphate resources while creating a more circular nutrient economy.
Beyond nutrient recycling, bone char offers additional environmental benefits. Its porous structure can improve soil water retention and create habitat niches for beneficial microorganisms. The material can also immobilize potentially toxic elements in soil, helping reduce the mobility of heavy metals such as lead, cadmium, and zinc.
Laboratory and field studies reviewed by the authors show that bone char can enhance soil fertility by gradually releasing phosphorus over time. This slow release mechanism may help improve plant growth while reducing nutrient losses that often occur with conventional fertilizers.
The properties of bone char depend strongly on how it is produced. Lower pyrolysis temperatures can promote nutrient availability, while higher temperatures increase surface area and adsorption capacity. These differences allow bone char to be tailored for different agricultural or environmental applications.
“Optimizing production conditions could allow us to design bone char materials that meet specific soil and crop needs,” the researchers noted.
The review also highlights knowledge gaps that must be addressed before bone char can be widely adopted. In particular, more long term field studies are needed to understand how bone char influences soil microbial communities, greenhouse gas emissions, and nutrient cycling over time.
Despite these challenges, the authors argue that bone char represents an underutilized resource with significant potential.
As global demand for food continues to rise and concerns grow about soil degradation and nutrient sustainability, innovative solutions that convert waste into agricultural resources will become increasingly important.
“Bone char offers a pathway to recover nutrients, improve soil health, and reduce environmental impacts simultaneously,” the authors said. “With further research and supportive policies, it could become an important component of sustainable agriculture.”
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Journal Reference: Ghorbani, M., Azarnejad, N., Brown, R.W. et al. Sustainable resource management with bone char—challenges and opportunities for enhancing soil health and phosphorus stocks. Biochar 8 , 34 (2026).
https://doi.org/10.1007/s42773-025-00550-3
About Biochar
Biochar (e-ISSN: 2524-7867) 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.
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Biochar
Literature review
Sustainable resource management with bone char—challenges and opportunities for enhancing soil health and phosphorus stocks
28-Feb-2026