Biochar and beneficial bacteria team up to unlock soil phosphorus and boost sustainable agriculture
image: Insights into the interfacial dynamics and interaction mechanisms between phosphate-solubilizing bacteria and straw-derived biochar
Credit: Zhe Wang, Bing Chen, Yiqi Cao, Sufang Xing, Baiyu Zhang, Shuguang Wang & Huifang Tian
A new study reveals how pairing biochar with beneficial soil bacteria could significantly improve phosphorus availability in soils, offering a sustainable alternative to conventional fertilizers and helping support global food production.
Phosphorus is an essential nutrient for plant growth, but it is often locked in forms that plants cannot use. Farmers frequently rely on chemical fertilizers to compensate, which can lead to environmental problems such as water pollution and algal blooms. Scientists have increasingly turned to phosphate-solubilizing bacteria, or PSB, as a natural solution because these microbes can convert unavailable phosphorus into forms plants can absorb.
Now, researchers have uncovered how biochar, a carbon-rich material made from agricultural waste, can enhance the performance of these bacteria by providing an ideal habitat for their growth and activity.
“Our findings show that biochar is not just a passive carrier, but an active partner that helps bacteria attach, grow, and function more effectively in soil,” said one of the study’s authors. “This opens new possibilities for designing more efficient and sustainable soil amendments.”
In the study, scientists examined how two common PSB species interact with biochar produced from cotton straw at different temperatures. Using advanced techniques such as atomic force microscopy and theoretical modeling, they observed how individual bacterial cells attach to biochar surfaces and form stable communities.
The results showed that biochar with higher production temperatures had larger surface areas and more favorable surface properties, allowing bacteria to adhere more strongly. This stronger attachment promotes the formation of biofilms, which are protective microbial communities that enhance bacterial survival and activity in challenging soil environments.
The researchers also discovered that bacterial attachment is not a simple process. Instead, it occurs in several stages. Initially, bacteria move freely in water and approach the biochar surface. They are then weakly attracted and temporarily trapped, before overcoming energy barriers through a combination of physical and biological interactions. Finally, they establish a stable but reversible attachment that leads to biofilm formation.
Importantly, this attachment process was closely linked to the production of extracellular polymeric substances, or EPS, which are sticky compounds made by bacteria. Higher levels of EPS were associated with stronger adhesion and more stable microbial communities.
The study highlights that biochar properties such as surface area, electrical conductivity, and water retention capacity play critical roles in supporting bacterial immobilization. These features create a microenvironment that protects bacteria from stress and enhances their ability to release phosphorus in soils.
By improving the efficiency of PSB, biochar-based inoculants could reduce the need for synthetic fertilizers while maintaining crop productivity. At the same time, using agricultural residues like cotton straw to produce biochar supports a circular economy and helps store carbon in soils.
The researchers note that while high-temperature biochar showed the strongest bacterial attachment, its high pH may require adjustment for practical agricultural use. Future work will focus on optimizing biochar properties and testing these systems in real field conditions.
Overall, the study provides new insights into the microscopic interactions between biochar and beneficial bacteria, offering a pathway toward more sustainable and resilient agricultural systems.
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Journal Reference: Wang, Z., Chen, B., Cao, Y. et al. Insights into the interfacial dynamics and interaction mechanisms between phosphate-solubilizing bacteria and straw-derived biochar. Biochar 7, 55 (2025).
https://doi.org/10.1007/s42773-025-00444-4
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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.