Monday, March 30, 2026

Cohesion in Diversity

A study by the Universities of Trento and NTU Singapore shows through brain scans that focusing on national identity help reduce distances between ethnic groups. Results published in PNAS

Università di Trento

The brain? It has a flexible social perception. In interactions with people from different ethnic groups, it tends to respond more inclusively when a shared national identity is made salient.

A study (National identity reconfigures brain responses from ‘them’ to ‘us’) by the University of Trento, Italy, and Nanyang Technological University, Singapore (NTU Singapore), published in the international journal Proceedings of the National Academy of Sciences (PNAS), sheds light on the underlying neural mechanisms.

The findings help to better understand the relationship between ethnic and national identity and have implications for improving intergroup relations in multicultural societies.

The study shows that the brain’s representation of social boundaries can rapidly reorganise in response to context. The research team suggests that this neural flexibility underlies the human ability to navigate complex social environments characterised by multiple and interconnected group identities. Understanding these mechanisms is crucial for developing effective strategies to bridge divisions and foster more harmonious intergroup relations.

The research demonstrates that even a brief reminder of a shared national identity (such as hearing a common language or seeing the flag of one's country) can alter the brain’s response when viewing faces of people from different ethnic groups. In particular, a region of the frontal cortex - key for relating others to the self - shows increased engagement when processing faces from ethnic out-groups. Functional MRI reveals that the brain begins to categorise these faces as part of one’s own group, while still preserving information about ethnic differences.

Gianluca Esposito, co-lead of the project and Director of the Department of Psychology and Cognitive Science at the University of Trento, comments: “This study shows that the human brain has a remarkable capacity to expand the sense of belonging, shifting from a ‘us versus them’ mindset to a more inclusive ‘we.’ When a shared identity, such as a national one, becomes salient, individuals outside one’s group begin to be perceived more similarly. This suggests that, even in contexts marked by ethnic or social divisions, there are neuropsychological foundations that can support mutual recognition, reduce distance, and foster greater openness toward others. From a social cohesion perspective, these findings indicate that emphasising common identities and shared goals can help defuse oppositional dynamics and create more favourable conditions for dialogue. The most encouraging message is that social boundaries are not fixed: the brain is capable of reorganising itself, providing a concrete basis for envisioning pathways toward coexistence, reconciliation, and lasting peace.”

Annabel Chen, co-lead of the project, Director, Cradle@NTU and President's Chair in Psychology at NTU Singapore, adds: “What is striking is that the brain does not seem to need to erase ethnic identity in order to make room for a shared national identity. Our findings suggest that these identities can coexist, and that reminding people of a common national identity can shift social perception in a more inclusive direction. For multicultural societies, this points to an important principle: efforts to strengthen social cohesion may be more effective when they affirm both shared belonging and subgroup identities, rather than treating ethnic identity as something that must be set aside.”

Kelly Sng, PhD candidate at NTU Singapore and first author of the study, explains: “We found that the brain is more flexible in social perception than often assumed. Even a brief identity cue was enough to change how faces of out-group members were processed, but the change was not absolute. The brain continued to track ethnic distinctions, suggesting that social harmony does not require people to give up who they are.”

About the study

The study was conducted in Singapore, where the multiethnic population and clearly defined ethnic and national identities provide a natural context for examining these questions.

The 92 participants belonged to the three main ethnic communities in Singapore: Chinese, Malay, and Indian. Their brain activity was measured using functional magnetic resonance imaging (fMRI) while they viewed faces of individuals from different ethnic groups.

The study used both auditory stimuli - short spoken phrases in different languages - and visual stimuli - cultural symbols associated with ethnic or national identity. Faces were presented under two conditions: after exposure to ethnic identity cues (reminders of one’s own or others’ ethnicity) and after exposure to national identity cues (reminders of belonging to Singapore).

About the article

The article, titled “National identity reconfigures brain responses from ‘them’ to ‘us’” (DOI 10.1073/pnas.2531563123), was published on March 30, 2026. Corresponding authors are Gianluca Esposito (University of Trento) and SH Annabel Chen (Nanyang Technological University, Singapore).

The paper is also authored by Kelly H.L. Sng (first author) and Nisha Syed Nasser, both members of the Singapore research team. The article is available at: www.pnas.org/doi/10.1073/pnas.2531563123

Journal

Proceedings of the National Academy of Sciences

DOI

10.1073/pnas.2531563123

Method of Research

Imaging analysis

Subject of Research

People

Article Title

National identity reconfigures brain responses from ‘them’ to ‘us'

Article Publication Date

30-Mar-2026

A new way to deliver faster, greener wireless connections indoors

A chip‑scale laser array with integrated beam shaping enables ultrafast, energy‑efficient optical wireless links for indoor networks

SPIE--International Society for Optics and Photonics

Chip-scale platform integrating the 5x5 VCSEL array and custom beam-shaping optics — image:
*The image conceptually represents the compact, chip-scale platform integrating the 5x5 VCSEL array and custom beam-shaping optics to create a structured grid of uniform square spots.*
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Credit: Image courtesy of H. Safi (University of Cambridge)

Modern life depends on fast and reliable wireless connections. Video calls, streaming services, virtual reality, and smart devices all place growing demands on networks that already serve billions of users. Most wireless data today travels through radio-based technologies such as Wi-Fi and cellular systems. While these approaches have been highly successful, they face mounting challenges, including crowded radio spectrum, interference in dense indoor spaces, and rising energy consumption as more devices come online.

A promising complementary approach is optical wireless communication, which uses light instead of radio waves to transmit data. Light offers far more bandwidth than radio frequencies, does not interfere with existing wireless systems, and can be directed precisely at specific locations. These features make optical wireless links particularly attractive for indoor environments such as offices, homes, data centers, hospitals, and public venues, where many users need high-speed connections in close proximity.

In a study reported in Advanced Photonics Nexus, researchers demonstrate a compact optical wireless transmitter that combines very high data rates with improved energy efficiency. The system is built around a small chip containing an array of tiny semiconductor lasers and a carefully designed optical setup that shapes how light is delivered to users. Together, these elements form a scalable platform for high-capacity indoor wireless communication.

Sending data with many tiny lasers

At the heart of the system is a custom-made 5 × 5 array of vertical-cavity surface-emitting lasers, or VCSELs. These lasers emit infrared light and are widely used in data centers and sensing applications because they can operate efficiently and be modulated at high speeds. Importantly, VCSELs can be fabricated in large arrays using standard semiconductor manufacturing techniques.

In this work, each laser in the array is individually addressable and can transmit its own data stream. By operating many lasers in parallel, the researchers were able to increase the total data capacity far beyond what a single light source could deliver. The entire laser array fits on a chip less than a millimeter in size, making it compatible with compact wireless access points or even can be easily integrated into devices like smartphones.

The team fabricated the laser array using established semiconductor processes and mounted the finished chip onto a custom circuit board. Initial tests showed that the lasers performed consistently across the array, producing stable output power and supporting high-speed modulation.

High-speed optical wireless links

To evaluate performance, the researchers set up a free-space optical link spanning two meters. Each laser was driven using a modulation technique that divides the data into many closely spaced frequency channels, allowing the system to make efficient use of the available bandwidth while adapting to variations in signal quality.

In the experiments, 21 of the 25 lasers were operational. Individual lasers achieved data rates between about 13 and 19 gigabits per second. When combined, the system reached an aggregate data rate of 362.7 gigabits per second. This represents one of the highest reported throughputs for a chip-scale optical wireless transmitter using a free-space coupled receiver.

The researchers note that the achieved speeds were limited by the bandwidth of the commercial photodetector used in the measurements. With faster receivers, the same transmitter architecture could support even higher data rates.

Shaping light for multiple users

Sending many beams of light at once introduces new challenges. If beams overlap too much, signals can interfere with one another, making it difficult for receivers to separate the data streams. To address this, the team designed a compact optical system that shapes and steers the light emitted by the laser array.

A custom microlens array first collimates the light from each laser. Additional lenses then redistribute the beams into a structured grid of square illumination spots at the receiver plane. This arrangement ensures that each beam covers a defined area with minimal overlap.

Measurements showed that the shaped beams achieved more than 90 percent uniformity across the illuminated region at a distance of two meters. This structured illumination makes it possible to assign different beams to different users or devices in the same room.

The researchers also tested multiuser operation by activating several lasers simultaneously. In a demonstration with four active beams, each link maintained stable communication, and the system delivered a combined data rate of about 22 gigabits per second. The results show that multiple optical wireless links can operate in parallel without significant interference.

Lower energy use per bit

Energy efficiency is a key concern for future wireless networks, especially as data traffic continues to grow. Traditional radio-based systems require increasing amounts of power to deliver higher data rates, which can become costly and environmentally burdensome.

The optical wireless system demonstrated here uses laser sources that are naturally power efficient and can be driven directly at high speed. As a result, the energy required to transmit each bit of data is significantly lower than in typical Wi-Fi systems. The researchers measured an energy consumption of about 1.4 nanojoules per bit, roughly half that reported for state-of-the-art Wi-Fi under comparable conditions.

Complementing existing wireless networks

The researchers emphasize that optical wireless communication is not intended to replace Wi-Fi or mobile networks, but to complement them. Optical links could be deployed in rooms, offices, factories, or other indoor spaces where high capacity is needed, offloading traffic from crowded radio networks.

In the future, similar systems could be integrated into lighting fixtures, ceilings, or access points, providing fast, secure, and energy-efficient wireless connections to many users at once. By combining laser arrays, high-speed data transmission, and carefully designed optics in a compact platform, this work outlines a practical path toward next-generation indoor wireless networks that deliver higher performance without a corresponding increase in energy use.

For details, see the original Gold Open Access article by H. Safi et al., “Chip-scale beam-shaped optical wireless system for high-speed and energy-efficient connectivity," Adv. Photon. Nexus 5(2) 026008 (2026), doi: 10.1117/1.APN.5.2.026018

Journal

Advanced Photonics Nexus

DOI

10.1117/1.APN.5.2.026018

Subject of Research

Not applicable

Article Title

Chip-scale beam-shaped optical wireless system for high-speed and energy-efficient connectivity

Half of Medicaid beneficiaries could lose coverage if Medicaid work requirements in the ‘One Big Beautiful Bill’ are extended nationally

Abstract: https://www.acpjournals.org/doi/10.7326/ANNALS-25-04811

A cross-sectional study suggests that if Congress were to impose Medicaid work requirements across the country, roughly half of adult enrollees could be at risk of losing coverage despite having higher rates of physical, cognitive, and daily‑living impairments. Researchers found that many of these adults report poor overall health, even though their impairments may not qualify them for formal disability exemptions. The study is published in Annals of Internal Medicine.

The One Big Beautiful Bill Act (H.R.1) implemented Medicaid work requirements for beneficiaries in some states, but congressional policymakers are considering extending work requirements nationally to all Medicaid enrollees. Researchers from Beth Israel Deaconess Medical Center’s Richard A. and Susan F. Smith Center for Outcomes Research analyzed data from the 2022–2023 Medical Expenditure Panel Survey to understand the health and functional status of adults aged 19 to 64 who did not meet typical exemption criteria and worked less than 20 hours a week who could lose Medicaid if federal work requirements were implemented. They found that about 8.3 million people, or 50.4% of this group, would be at risk of disenrollment. These adults had higher levels of physical, neuropsychological, and independent‑living impairments, and were more likely to report poor physical and mental health compared with those meeting work requirements. The authors conclude that many enrollees vulnerable to losing coverage have health challenges significant enough to limit their ability to meet work-hour rules, even if they do not qualify as formally disabled. The findings underscore the importance of revising exemption criteria to account for functional impairment and medical vulnerability.

Media contacts: For an embargoed PDF, please contact Gabby Macrina at gmacrina@acponline.org. To contact corresponding author Rishi K. Wadhera, MD, MPP, MPhil please email rwadhera@bidmc.harvard.edu.

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Journal

Annals of Internal Medicine

DOI

10.7326/ANNALS-25-03219

Method of Research

News article

Subject of Research

Peopl

Article Publication Date

31-Mar-2026

Common antidepressant eases fatigue associated with long COVID, study finds

McMaster University

A global research team co‑led by McMaster University has identified one of the first medications shown to meaningfully reduce fatigue in people living with long COVID – a breakthrough for millions still struggling with persistent symptoms years after the pandemic began.

The randomized, placebo‑controlled clinical trial found that fluvoxamine, a low‑cost and widely available antidepressant, significantly improved fatigue and quality of life among adults with long COVID. The findings were published March 31, 2026 in the Annals of Internal Medicine.

Fatigue is the most common and debilitating symptom of long COVID, leaving many people unable to work, care for their families, or resume their normal lives. Despite its global impact, few proven treatments exist.

“This is an important step forward for patients who have been desperate for evidence‑based options,” says Edward Mills, senior author, professor in McMaster’s Department of Health Research Methods, Evidence, and Impact, and co‑principal investigator of the trial. “Fluvoxamine showed consistent and meaningful benefits, and because it's already widely used and well understood, it has clear potential for clinical use.”

The study was co‑led by researchers in Canada, Brazil, and the United States, with clinical sites in the city of Belo Horizonte and across Minas Gerais, Brazil. The REVIVE-TOGETHER trial team included partners from McMaster University, the University of British Columbia, Stanford University, the University of Pittsburgh, Duke University, Georgetown University, and multiple Brazilian institutions.

The trial enrolled 399 adults in Brazil who continued to experience fatigue for at least 90 days after a confirmed SARS‑CoV‑2 infection. Participants were randomly assigned to receive fluvoxamine (sold under the brand name Luvox), metformin (a common diabetes medication), or placebo for 60 days.

“We wanted to test whether two existing, widely available, and affordable medications could help. Both had biological reasons to think they might work against long COVID fatigue, but neither had been rigorously tested for this purpose in a proper clinical trial,” says Mills.

The researchers found fluvoxamine reduced fatigue more than placebo, with evidence showing a 99 per cent probability the drug outperformed the placebo. The medication also produced improvements in overall quality of life across multiple measures.

Previous research has showed metformin reduces the risk of developing long COVID when taken during the acute phase of infection, and this research showed it offers no meaningful benefit in helping people with fatigue symptoms of established long COVID.

The study used a sophisticated Bayesian adaptive design, allowing researchers to stop treatment arms early when results became clear – a method that accelerates evidence generation while maintaining scientific rigour.

“The trial used a sophisticated adaptive design that allowed it to reach conclusions more efficiently than traditional trials, stopping early when the evidence was clear enough – a design innovation as important as the findings themselves,” says Gilmar Reis, lead author, researcher with Cardresearch, a Brazilian clinical research center based in Belo Horizonte. Reis is also a part-time associate professor at McMaster.

Long COVID remains a major public health challenge, affecting an estimated 65 million people worldwide. Yet most medical guidelines still offer only supportive care, such as pacing and symptom management, due to the lack of proven treatments. The researchers emphasize that while fluvoxamine offers a promising option for managing fatigue, long COVID is a complex condition with multiple symptoms and biological pathways. Further studies are needed to understand who benefits most, how the medication works, and how it might be combined with other emerging treatments.

“This trial gives clinicians their first strong evidence for a medication that helps reduce long COVID fatigue. Patients want something they can try today – and this finding brings us closer to that reality,” says Jamie Forrest, corresponding author and postdoctoral research fellow at the University of British Columbia.

The research was funded by The Latona Foundation.

Available for interview:

Edward Mills: millsej@mcmaster.ca

Senior author of the study and co‑principal investigator of the trial

Professor in McMaster’s Department of Health Research Methods, Evidence, and Impact

Gilmar Reis: reisg1@mcmaster.ca

Lead author of the study and co‑principal investigator of the trial

Associate professor in McMaster’s Department of Health Research Methods, Evidence, and Impact

Media contact: stranj4@mcmaster.ca

Journal

Annals of Internal Medicine

Biochar nanoparticles boost flowering by rewiring plant carbon flow and gene activity

Biochar Editorial Office, Shenyang Agricultural University

image:
Biochar nanoparticles enhance flowering in Gentiana szechenyii Kanitz. by modulating source-sink carbon allocation and gene expression
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Credit: Guopeng Chen, Lame Zeren, Chenghui Wang, Xuemei Wu, Yue Xu, Jie Zhang, Rong Ding, Hongmei Jia, Shihong Zhong & Rui Gu

A new study reveals that tiny particles derived from biochar can directly enter plant tissues and significantly enhance flowering by reshaping how plants allocate carbon and regulate key genes. The findings provide a new explanation for how biochar improves crop performance, beyond its well-known effects on soil fertility.

Biochar has long been promoted as a sustainable soil amendment that improves nutrient availability and supports plant growth. However, scientists have struggled to explain why plants often show improved flowering even when nutrients are already sufficient. The new research uncovers a previously overlooked mechanism involving biochar nanoparticles.

“Our results show that biochar is not just acting in the soil,” said the study’s corresponding author. “Nanoparticles released from biochar can move into plant cells, where they actively regulate metabolism and gene expression to promote flowering.”

The research team studied Gentiana szechenyii, a medicinal plant valued for its flowers. By carefully controlling nutrient levels, the researchers ensured that any observed effects were not due to changes in soil fertility. They found that applying biochar increased flower number by more than 24 percent, even though key soil nutrients remained unchanged.

Using advanced imaging techniques, the team observed that biochar nanoparticles accumulated inside plant cells, particularly in chloroplasts, the structures responsible for photosynthesis. This discovery provided direct evidence that nanoparticles can enter plant tissues and influence internal biological processes.

Further analysis revealed that these nanoparticles altered how plants manage carbon. Plants produce sugars such as sucrose in their leaves and transport them to growing tissues like flowers. In treated plants, genes involved in sugar production and transport were strongly activated. At the same time, carbon allocation shifted away from leaves and toward flowering structures.

This shift effectively strengthened what scientists call the “sink” capacity of flowers, meaning that more energy and resources were directed toward reproductive growth. As a result, plants produced more flowers, even though the size of individual flowers decreased slightly due to resource redistribution.

The study also showed that biochar nanoparticles influenced a wide range of genes related to flowering, hormone signaling, and floral development. These molecular changes worked together with altered carbon flow to drive the observed increase in flowering.

Importantly, the findings challenge the traditional view that biochar works mainly by improving soil conditions. Instead, the study demonstrates that biochar-derived nanoparticles can act directly inside plants as active regulators of growth.

“This opens up a new perspective on how biochar functions in agriculture,” the author explained. “We are now looking at biochar not only as a soil amendment, but also as a source of functional nanomaterials that interact with plants at the cellular level.”

The discovery has important implications for sustainable agriculture. By harnessing the unique properties of biochar nanoparticles, researchers may be able to design more efficient and targeted strategies to enhance crop yield and flowering without relying on additional fertilizers.

The study also highlights the broader potential of biochar nanotechnology. As scientists continue to explore how these particles interact with plant systems, new opportunities may emerge for improving plant productivity, resilience, and resource use efficiency.

While further research is needed to fully understand the underlying molecular pathways, this work provides strong evidence that biochar nanoparticles play a direct and active role in plant development. It also suggests that future agricultural innovations could combine soil management with nanoscale engineering to achieve more sustainable food production.

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Journal Reference: Chen, G., Zeren, L., Wang, C. et al. Biochar nanoparticles enhance flowering in Gentiana szechenyii Kanitz. by modulating source-sink carbon allocation and gene expression. Biochar 8, 62 (2026).

https://doi.org/10.1007/s42773-026-00570-7

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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.

Journal

Biochar

DOI

10.1007/s42773-026-00570-7

Method of Research

Experimental study

Article Title

Biochar nanoparticles enhance flowering in Gentiana szechenyii Kanitz. by modulating source-sink carbon allocation and gene expression

AI-guided biochar design offers new pathway to tackle emerging water pollutants

Biochar Editorial Office, Shenyang Agricultural University

image:
AI-driven biochar engineering for emerging pollutants removal from water: performance, mechanisms, and environmental perspectives
view more
Credit: Ojima Z. Wada, Gordon McKay, Tareq Al-Ansari & Khaled A. Mahmoud

Emerging pollutants such as pharmaceuticals, microplastics, and industrial chemicals are increasingly detected in water systems worldwide, raising concerns about long-term risks to ecosystems and human health. A new study highlights how artificial intelligence can transform biochar into a powerful, cost-effective solution for removing these persistent contaminants from water.

In a comprehensive review, researchers present a new framework that combines biochar engineering with artificial intelligence to design next-generation materials tailored for specific pollutants. The work outlines how advanced data-driven approaches can accelerate the development of sustainable water treatment technologies.

“Emerging pollutants are difficult to remove using conventional treatment methods, and their diversity makes the challenge even more complex,” said the corresponding author. “Our study shows that by combining biochar with artificial intelligence, we can design smarter materials that are both effective and scalable.”

Biochar, a carbon-rich material produced from biomass such as agricultural waste, has gained attention for its environmental benefits and low production cost. Compared to advanced nanomaterials, which can cost thousands to millions of dollars per ton, biochar can be produced for around 144 dollars per ton, making it an attractive option for large-scale water treatment.

However, pristine biochar has limitations. Its pollutant removal performance is often moderate and largely relies on physical adsorption processes. To address this, the researchers propose a tiered strategy that classifies biochar systems into three levels: pristine biochar, modified biochar, and advanced biochar composites.

At the basic level, pristine biochar removes contaminants through mechanisms such as pore filling, hydrophobic interactions, and electrostatic attraction. Modified biochar enhances these capabilities by introducing functional groups or increasing surface area through activation and doping techniques. At the highest level, biochar composites integrate materials such as nanoparticles or graphene, enabling additional mechanisms including catalytic degradation and photocatalysis.

The study highlights that while advanced composites can achieve superior performance, they often face challenges related to cost, scalability, and environmental safety. As a result, the researchers advocate for a balanced approach that prioritizes simpler biochar systems where effective and reserves complex materials for more challenging pollutants.

A key innovation in the study is the integration of artificial intelligence to guide material design. Machine learning models can analyze large datasets to predict how factors such as feedstock type, pyrolysis conditions, and surface chemistry influence pollutant removal. These models can identify optimal combinations of parameters, significantly reducing the need for time-consuming trial-and-error experiments.

For example, AI models can predict how changes in biochar structure affect its ability to remove specific contaminants such as PFAS, pharmaceuticals, or microplastics. By linking material properties with pollutant characteristics, researchers can design targeted solutions that maximize efficiency under real-world conditions.

The study also emphasizes the importance of scalability and environmental impact. While laboratory studies demonstrate high performance, real-world applications must consider factors such as production cost, energy use, and potential ecotoxicity. The authors call for standardized datasets, green synthesis methods, and more pilot-scale studies to bridge the gap between research and implementation.

“Our goal is not just to develop high-performance materials, but to ensure they can be safely and economically deployed at scale,” the author added.

By combining sustainable materials with advanced computational tools, the research provides a roadmap for tackling one of the most pressing challenges in water treatment. The findings suggest that AI-guided biochar engineering could play a critical role in safeguarding global water resources in the years ahead.

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Journal Reference: Wada, O.Z., McKay, G., Al-Ansari, T. et al. AI-driven biochar engineering for emerging pollutants removal from water: performance, mechanisms, and environmental perspectives. Biochar 8, 61 (2026).

https://doi.org/10.1007/s42773-025-00565-w

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About Biochar

Journal

Biochar

DOI

10.1007/s42773-025-00565-w

Method of Research

Literature review

Article Title

AI-driven biochar engineering for emerging pollutants removal from water: performance, mechanisms, and environmental perspectives

Biochar can curb methane emissions in rice fields, but nitrogen levels make the difference

Biochar Editorial Office, Shenyang Agricultural University

image:
Mineral nitrogen input modulates the methane mitigation potential of biochar in rice systems: based on meta-analysis and field experiment demonstration
view more
Credit: Weijie Huang, Xingyan Liu, Yu Deng, Daoyuan Zhao, Jun Yuan, Qirong Shen & Chao Xue

A new study reveals that biochar, a carbon-rich material increasingly promoted for sustainable agriculture, can significantly reduce methane emissions from rice paddies. However, its climate benefits depend strongly on how much nitrogen fertilizer is applied.

Rice cultivation is a major global source of methane, a potent greenhouse gas. As rice feeds nearly half of the world’s population, finding ways to reduce emissions without compromising food production is a critical challenge. In this new research, scientists combined large-scale data analysis with field experiments to better understand how biochar influences methane emissions in rice systems.

“Our results show that biochar has strong potential to mitigate methane emissions, but this benefit is not guaranteed,” said the study’s corresponding author. “It depends on how farmers manage nitrogen inputs.”

The research team analyzed 146 datasets from 51 independent studies worldwide, using advanced statistical approaches including network meta-analysis and machine learning methods. They compared different organic amendments commonly used in agriculture, such as straw, compost, manure, and biochar.

The findings were clear. Among all materials tested, biochar consistently showed the lowest methane emissions. In contrast, straw and manure tended to increase emissions significantly.

However, the study also uncovered an important caveat. The amount of mineral nitrogen fertilizer applied to fields emerged as the most influential factor controlling biochar’s effectiveness. When nitrogen inputs remained below approximately 291 kilograms per hectare, biochar reduced methane emissions. But when nitrogen levels exceeded this threshold, biochar actually increased methane emissions.

To validate these findings, the researchers conducted field experiments in a rice growing region in eastern China. The results confirmed the pattern observed in the meta-analysis. Under high nitrogen conditions, biochar significantly increased methane fluxes and emission potential compared to control treatments.

This counterintuitive effect may be explained by interactions between nitrogen, microbes, and carbon cycling in flooded soils. High nitrogen levels can stimulate plant growth and microbial activity, providing more substrates for methane-producing microorganisms. At the same time, excess nitrogen may suppress methane oxidation, tipping the balance toward higher emissions.

The study also identified another important factor: the carbon to nitrogen ratio of biochar itself. Biochar with lower ratios, typically derived from crop residues, showed stronger methane reduction potential. This suggests that both material design and field management must be considered together.

“These findings highlight that biochar is not a one-size-fits-all solution,” the authors noted. “Its climate benefits depend on aligning biochar properties with appropriate fertilizer management.”

The implications are significant for sustainable agriculture and climate mitigation. Biochar has been widely proposed as a carbon-negative technology that can improve soil health while reducing greenhouse gas emissions. This study suggests that its effectiveness in rice systems can be optimized through careful control of nitrogen inputs.

By integrating global data with real-world experiments, the research provides one of the most comprehensive assessments to date of how biochar interacts with agricultural management practices to influence methane emissions.

As policymakers and farmers look for practical ways to reduce agriculture’s climate footprint, the study offers a clear message. Biochar can be a powerful tool, but only when used under the right conditions.

“Optimizing nitrogen management is key to unlocking the full mitigation potential of biochar,” the authors said.

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Journal Reference: Huang, W., Liu, X., Deng, Y. et al. Mineral nitrogen input modulates the methane mitigation potential of biochar in rice systems: based on meta-analysis and field experiment demonstration. Biochar 8, 60 (2026).

https://doi.org/10.1007/s42773-025-00563-y

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About Biochar

Journal

Biochar

DOI

10.1007/s42773-025-00563-y

Method of Research

Experimental study

Article Title

Mineral nitrogen input modulates the methane mitigation potential of biochar in rice systems: based on meta-analysis and field experiment demonstration

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Monday, March 30, 2026

Cohesion in Diversity

Journal

DOI

Method of Research

Subject of Research

Article Title

Article Publication Date

A new way to deliver faster, greener wireless connections indoors

Journal

DOI

Subject of Research

Article Title

Journal

DOI

Method of Research

Subject of Research

Article Publication Date

Common antidepressant eases fatigue associated with long COVID, study finds

Journal

Biochar nanoparticles boost flowering by rewiring plant carbon flow and gene activity

Journal

DOI

Method of Research

Article Title

AI-guided biochar design offers new pathway to tackle emerging water pollutants

Journal

DOI

Method of Research

Article Title

Biochar can curb methane emissions in rice fields, but nitrogen levels make the difference

Journal

DOI

Method of Research

Article Title

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