The dose-dependent effects of dissolved biochar on C. elegans: Insights into the physiological and transcriptomic responses

Researchers have uncovered how dissolved biochar—tiny carbon particles derived from burning plant material—affects soil nematodes, shedding light on both benefits and risks to these important ecosystem players. The study focused on the common laboratory worm, Caenorhabditis elegans, revealing that the impact of dissolved biochar strongly depends on the amount present in the environment.

The team found that when nematodes were exposed to low concentrations of dissolved biochar, their growth and physical activity increased. These smaller doses likely functioned as extra nutrients or provided mild stimulation that encouraged development. However, higher levels of biochar led to a slowdown in growth and triggered signs of metabolic stress, as demonstrated by changes in both the worms' physiology and gene activity.

To understand how these effects occur, scientists tracked the worms' movement, growth, and reproductive patterns, and carried out RNA sequencing to analyze thousands of genes. They observed a "hormetic effect": lower doses helped nematodes thrive, while higher doses disrupted normal metabolic and cellular functions, including pathways involved in stress resistance and even cell death. Importantly, key genes related to growth, stress response, and movement were sensitive to biochar concentration, emphasizing the complexity of the molecular response.

The findings serve as a timely warning to agricultural decision-makers. While biochar is widely promoted for its profits in soil health and carbon sequestration, its dissolved fraction can travel through soils and interact directly with living organisms—sometimes in ways that may harm non-target species. This work highlights the need for careful dosing and oversight when deploying biochar in real-world agricultural systems to ensure safe, sustainable practices.

Researchers recommend further exploration of biochar's long-term impacts on soil nematodes and other wildlife to better understand how best to balance soil restoration with ecological safety. The study illustrates the growing importance of molecular biology tools in environmental risk assessment and sustainable agriculture innovation.

=== 

Journal Reference:  Wang, X., Li, J., Luo, L. et al. The dose-dependent effects of dissolved biochar on C. elegans: insights into the physiological and transcriptomic responses. Biochar 7, 100 (2025). https://doi.org/10.1007/s42773-025-00493-9  

=== 

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. 

Follow us on Facebook, X, and Bluesky.