Biochar and friendly bacteria team up to help flowers thrive
image: Biochar and Bacillus subtilis boost cut chrysanthemum growth via intensified microbial interkingdom interactions
Credit: Rui Tao, Wangying Ding, Keyi Zhang, Shuoshuo Wu, Jun Li, Guixin Chu & Baowei Hu
A new study by researchers in China reveals that combining biochar, a charcoal-like soil enhancer, with a beneficial soil bacterium can help boost the growth and health of cut chrysanthemums, a commercially important flower troubled by soil disease from long-term monoculture. This simple, eco-friendly approach could hold promise for sustainable farming of many crops facing similar challenges.
Cut chrysanthemums are one of the world’s most popular cut flowers, widely appreciated for their vibrant blooms and economic value. In China alone, over 7,000 hectares are devoted to growing these flowers, with billions sold each year. However, years of growing the same crop have caused major problems for farmers. The soil becomes infested with harmful fungi like Fusarium oxysporum, leading to wilt disease, poor yields, and heavy economic losses.
Many growers currently rely on pesticides and chemical treatments to manage these issues, but such methods can harm soil health and conflict with sustainable agriculture goals. Crop rotation is effective but often unfeasible, given the need for high productivity. The search for greener solutions has brought researchers to test natural methods that restore balance to the soil’s microscopic community.
In this new research, the scientists explored whether adding biochar and a beneficial bacterium, Bacillus subtilis, could help cut chrysanthemums fight off disease and thrive in soil heavily impacted by continuous cropping. Biochar is made by heating plant matter in the absence of oxygen and is already known to improve soil structure and support good microbes. Bacillus subtilis is a common “good” bacterium found in soil, recognized for its ability to suppress plant pathogens.
The team conducted greenhouse trials using soil collected from a field that had grown only chrysanthemums for 12 years and suffered from severe Fusarium wilt. They compared four treatments: no amendment, biochar alone, Bacillus subtilis alone, and both together. Over several months, they tracked plant growth, disease levels, and the diversity and makeup of soil microbes.
The results were striking. Adding both biochar and Bacillus subtilis outperformed either alone, leading to healthier plants with 41 percent more biomass and over twice the root activity compared to untreated controls. The combined treatment sharply reduced Fusarium wilt disease to under 20 percent, the lowest among all groups.
Soil analysis showed a major shift in the underground microbial community. The dual treatment increased the overall diversity of both bacteria and fungi—generally a sign of robust soil health. Beneficial bacteria, including more Bacillus and Pseudomonas, flourished, while populations of harmful fungi like Fusarium dropped. The study also uncovered a rise in positive, mutually supportive interactions between different kinds of microbes, especially between bacteria and fungi. According to the researchers, this microbial teamwork is key to suppressing disease.
Statistical modeling confirmed that these enhanced cross-kingdom interactions, sparked by the use of biochar and Bacillus subtilis together, explained most of the gains in plant health and growth. The findings suggest that combined microbial and organic soil amendments could present a practical solution to chronic soil sickness in flower and crop production.
While the experiment was conducted in pots under greenhouse conditions, the researchers are optimistic about the technique’s potential for use in farms and gardens worldwide. They note, however, that field trials over several years and in other crops are needed to fully understand how the method performs in different real-world settings.
This research adds to the growing body of evidence that nurturing soil microbes, and promoting their cooperation, is essential for sustainable agriculture. By harnessing the natural synergy between biochar and Bacillus subtilis, farmers may soon have a powerful new tool for healthier crops and more resilient soils.
===
Journal Reference: Tao, R., Ding, W., Zhang, K. et al. Biochar and Bacillus subtilis boost cut chrysanthemum growth via intensified microbial interkingdom interactions. Biochar 7, 75 (2025).
https://doi.org/10.1007/s42773-025-00466-y
===
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.