Two paths to healthier soils: Scientists reveal how straw and biochar store carbon differently
Adding straw or biochar to manure can help salt-affected soils capture more carbon, but new research reveals that the two materials achieve this through fundamentally different mechanisms
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Divergent pathways of straw versus biochar integration with manure to enhance SOC sequestration in coastal saline soils
view moreCredit: Xiaolong Bai, Jie Zhou, Ruixiao Dong, Shang Wang, Mengmeng Chen, Jing Wang, Xiaobin Li, Haoruo Li, Gilles Colinet, Hongyuan Zhang & Yuyi Li
Soils are among the planet's largest carbon reservoirs, yet salinity and land degradation threaten their ability to store carbon and support agriculture. Improving carbon storage in salt-affected farmland could therefore offer a dual benefit: restoring soil health while supporting climate change mitigation.
In a study published in Biochar, researchers from the Chinese Academy of Agricultural Sciences and collaborating institutions discovered that combining manure with straw or biochar significantly increased soil organic carbon, but through two distinct pathways. Straw primarily stimulated microbial activity and carbon transformation, while biochar improved soil structure and the physical protection of carbon.
"Both straw and biochar can improve carbon storage in saline soils, but they work in different ways," said Hongyuan Zhang, a corresponding author of the study. "Understanding these differences is essential for developing soil management strategies that improve fertility and support carbon sequestration."
The researchers conducted a two-year field experiment in China's Yellow River Delta, where high soil salinity and low organic matter levels pose major challenges to agricultural productivity. Four fertilizer treatments were compared, including conventional chemical fertilizer, manure supplementation, and manure combined with either straw or biochar.
The team examined soil carbon, microbial communities, enzyme activities, and soil pore structures to understand how each treatment influenced carbon accumulation.
Both straw and biochar combinations increased soil organic carbon by approximately 19% compared with manure alone in 2023. However, the underlying processes differed substantially.
When straw was combined with manure, it provided readily available organic materials that stimulated soil microorganisms. This increased carbon-cycling enzyme activities and promoted the accumulation of microbial necromass, the remains of dead microorganisms that contribute to soil organic matter.
Compared with manure alone, the straw treatment increased microbial necromass carbon by 10.8% and fungal necromass carbon by 11.2%. These findings suggest that microbial processing plays an important role in transforming straw-derived carbon into soil carbon.
Biochar followed a different route. Rather than primarily stimulating microbial carbon transformation, it enhanced soil aggregation and pore structure, helping protect organic carbon within larger soil particles.
The biochar treatment increased large soil aggregates by 40.9% and improved aggregate stability by 31.9%, compared with manure alone. It also increased soil porosity, creating a more favorable physical environment for carbon retention.
Microbial community analyses revealed another important distinction. Straw reduced the abundance of certain Actinobacteria-dominated microbial groups, while biochar promoted fungal groups dominated by Ascomycota that were positively associated with soil carbon storage.
Together, these findings highlight two complementary carbon sequestration strategies: biological transformation driven by straw and physical protection enhanced by biochar.
The researchers emphasize that longer-term field observations are needed to determine how these mechanisms influence carbon persistence over time.
"Our findings show that selecting organic amendments should involve more than measuring how much carbon they add to soil," Zhang explained. "Understanding how carbon is processed and protected can help guide more effective restoration of degraded agricultural land."
The study provides new insights for improving saline soil management, supporting sustainable agriculture, and strengthening soil-based carbon sequestration strategies.
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Journal Reference: Bai, X., Zhou, J., Dong, R. et al. Divergent pathways of straw versus biochar integration with manure to enhance SOC sequestration in coastal saline soils. Biochar 8, 139 (2026).
https://doi.org/10.1007/s42773-026-00656-2
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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.
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Journal
Biochar
Method of Research
Experimental study
Article Title
Divergent pathways of straw versus biochar integration with manure to enhance SOC sequestration in coastal saline soils
Article Publication Date
8-Oct-2026
Turning agricultural waste into soil-building substances: Manganese-modified biochar gives fungi a powerful boost
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Manganese-modified biochar enhances white-rot fungi-mediated lignocellulose humification: insights from molecular transformation and multi-omics analyses
view moreCredit: Feng Wang, Linjie Zhang, Feng Zhou, Wenyue Wang, Yinglong Su, Dongmei Zhou, Seungkwan Hong, Min Zhan & Bing Xie
A new study reveals how manganese-modified biochar helps beneficial fungi break down agricultural residues and accelerate the formation of valuable humic substances, offering a promising approach to sustainable organic waste recycling and soil improvement.
Agricultural residues such as wheat straw are produced in enormous quantities worldwide. Although these materials contain valuable organic carbon, their tough plant fibers resist decomposition, making efficient recycling a major challenge. Now, researchers have discovered that combining manganese-modified biochar with white-rot fungi can significantly improve the conversion of agricultural waste into humic substances, which are essential for soil fertility, carbon cycling, and ecosystem health.
The study, published in Biochar, demonstrates that this combination accelerates the breakdown of plant materials while promoting the formation of more complex and stable organic compounds.
"Agricultural waste is not simply something to dispose of. It is a valuable carbon resource that can be transformed into materials that support healthier soils," said the research team. "Our findings reveal how manganese-modified biochar can work together with beneficial fungi to make this transformation more efficient."
Humic substances are important components of soil organic matter. They help improve soil structure, support nutrient retention, and regulate carbon cycling. However, their natural formation is slow. Accelerating this process, known as humification, could provide new opportunities to recycle agricultural residues into valuable soil amendments.
To investigate this possibility, researchers combined manganese-modified biochar, produced from bamboo-derived biochar, with the white-rot fungus Phanerochaete chrysosporium. They then conducted a 35-day fermentation experiment using wheat straw.
The results were striking. With 5% manganese-modified biochar, lignin degradation increased by 93.4%, cellulose degradation by 77.0%, and hemicellulose degradation by 30.9% compared with the fungus-only control. Even more importantly, humic acid content increased by 47.7%, while an indicator of humic substance polymerization rose by 112.4%.
These improvements suggest that the treatment not only accelerates plant fiber decomposition but also promotes the formation of more complex humic materials.
To understand the underlying mechanisms, the researchers combined advanced molecular analysis, interpretable machine learning, and multi-omics techniques.
They discovered that manganese-modified biochar enhances fungal growth and stimulates enzymes responsible for breaking down resistant plant fibers. Manganese-associated oxidation reactions also contribute to this process, helping release smaller organic molecules that serve as building blocks for humic substances.
Molecular analysis further revealed that the treatment promotes specific chemical transformations, including deamination, dealkylation, and lignin breakdown. These changes favor the formation of more aromatic, oxygen-rich, and structurally complex humic-like substances, particularly through pathways involving polyphenols and quinones.
Meanwhile, gene expression and metabolite analyses showed enhanced activity in pathways associated with plant fiber degradation and the production of humification precursors.
Together, these findings reveal a coordinated process in which biochar, manganese, and fungi work synergistically to accelerate organic matter transformation.
The researchers believe this strategy could support more efficient recycling of lignocellulose-rich agricultural wastes and the development of sustainable soil amendment technologies.
However, further research is needed to evaluate manganese release, long-term environmental safety, and economic feasibility under practical operating conditions.
By uncovering the molecular mechanisms behind accelerated humification, this study provides a scientific foundation for transforming agricultural residues into valuable organic resources and advancing sustainable waste management.
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Journal Reference: Wang, F., Zhang, L., Zhou, F. et al. Manganese-modified biochar enhances white-rot fungi-mediated lignocellulose humification: insights from molecular transformation and multi-omics analyses. Biochar 8, 140 (2026).
https://doi.org/10.1007/s42773-026-00659-z
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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.
Follow us on Facebook, X, and Bluesky.
Journal
Biochar
Method of Research
Experimental study
Article Title
Manganese-modified biochar enhances white-rot fungi-mediated lignocellulose humification: insights from molecular transformation and multi-omics analyses
Article Publication Date
9-Oct-2026
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