Hydrochar turns agricultural waste into a powerful tool for healthier, carbon-rich soils
Biochar Editorial Office, Shenyang Agricultural University
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Hydrochar as an effective amendment for enhancing soil aggregation and carbon sequestration: evidence from comparative microcosm experiments
view moreCredit: Liyang Sun, Jim J. Wang, Sun Wei, Pingping Ye, Yue Deng, Xiangtian Meng, Ronghua Li, Zongsheng Zhang, Xiaoxuan Su & Ran Xiao
A new study shows that hydrochar, a carbon-rich material made from wet biomass, can improve soil structure and help soils store more carbon more effectively than several common organic amendments.
Healthy soil depends on two closely linked foundations: stable soil aggregates and sufficient soil organic carbon. Together, they help soil retain water, cycle nutrients, support plant roots, and resist erosion. Yet many agricultural soils remain carbon-deficient, and commonly used amendments such as straw, manure, and conventional biochar do not always improve both soil carbon storage and soil structure at the same time.
Now, researchers report that hydrochar may offer a promising dual solution. In a microcosm incubation study published in Biochar, the team compared hydrochar with maize straw and straw-derived biochar in purple soil, a widely distributed agricultural soil type in China. They also tested hydrochars made from different feedstocks, including maize straw, pig manure, and Zanthoxylum stalks.
“Our results show that hydrochar is not just another carbon amendment. It can actively help rebuild soil structure while also increasing soil carbon storage,” said corresponding author Ran Xiao. “This dual function is especially important for carbon-deficient croplands where both fertility and physical stability need improvement.”
Hydrochar is produced through hydrothermal carbonization, a process that converts wet organic biomass into a carbon-rich solid under moderate temperature and pressure. Unlike conventional biochar, which is produced by dry pyrolysis at higher temperatures, hydrochar often contains both labile carbon fractions that can stimulate microbial activity and more stable carbon fractions that can persist in soil.
In the study, hydrochar treatments substantially increased the proportion of macroaggregates, the larger and more stable soil particles that protect organic carbon from rapid decomposition. Hydrochars also improved mean weight diameter, a key indicator of aggregate stability, and increased soil organic carbon compared with the untreated control. Among the feedstocks, Zanthoxylum stalk-derived hydrochar showed particularly strong performance, delivering high carbon retention and strong improvements in aggregate stability.
The researchers found that the mechanisms behind these benefits were not driven by carbon content alone. Dissolved organic carbon, microbial activity, lignin-derived compounds, and the balance between labile and recalcitrant carbon fractions all played important roles. Hydrochar-originated carbon was mainly stored as particulate organic matter and accumulated in macroaggregates, suggesting that physical protection within soil structure helped stabilize newly added carbon.
Feedstock selection also mattered. Pig manure-derived hydrochar supplied more nutrients and promoted microbial biomass carbon, while stalk-derived hydrochar was more effective for carbon retention and soil aggregation. This means hydrochar production could potentially be tailored for different agricultural goals, such as improving fertility, increasing carbon storage, or enhancing soil structure.
“Choosing the right feedstock is critical,” said corresponding author Xiaoxuan Su. “A manure-based hydrochar may be useful when nutrient supply is the priority, while a lignocellulosic stalk-based hydrochar may be better suited for long-term carbon sequestration and aggregate stability.”
The findings point to a practical opportunity for sustainable agriculture: transforming agricultural and livestock residues into targeted soil amendments. By converting waste biomass into hydrochar, farmers and land managers may be able to improve soil quality while contributing to carbon management.
Although the study was conducted under controlled microcosm conditions, the authors note that it provides mechanistic evidence for future field trials. The work suggests that hydrochar could become a customizable amendment for climate-smart soil management, helping croplands store more carbon, form stronger soil aggregates, and support more resilient agricultural systems.
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Journal Reference: Sun, L., Wang, J.J., Wei, S. et al. Hydrochar as an effective amendment for enhancing soil aggregation and carbon sequestration: evidence from comparative microcosm experiments. Biochar 8, 69 (2026).
https://doi.org/10.1007/s42773-025-00547-y
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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
Hydrochar as an effective amendment for enhancing soil aggregation and carbon sequestration: evidence from comparative microcosm experiments
Not all biochar is equal: New perspective calls for clearer claims in carbon removal and soil health
A new perspective published in Biochar warns that biochar’s long-term carbon storage potential and its soil improvement benefits should not be treated as the same thing. The authors argue that clearer communication is urgently needed as biochar becomes a major player in voluntary carbon markets and climate mitigation strategies.
Biochar, a carbon-rich material produced by heating organic residues under low-oxygen conditions, is widely promoted for both carbon dioxide removal and agricultural benefits. However, the paper explains that these two goals often require different types of biochar. Highly stable biochar, often produced at higher pyrolysis temperatures, can store carbon for long periods but tends to be more chemically inert. In contrast, lower-temperature biochar may retain more surface functional groups that help support nutrient retention, water retention, microbial activity, and pollutant stabilization, but it may not be as durable for long-term carbon storage.
“Biochar is not a single, uniform product,” said lead author Robert W. Brown. “A biochar designed for durable carbon removal may not deliver the same soil benefits as one designed as a soil conditioner. Recognizing this distinction is essential for credible science, policy, and carbon markets.”
The authors highlight that feedstock type, pyrolysis temperature, and resulting chemical properties, especially hydrogen to carbon and oxygen to carbon ratios, should be reported more consistently. Without these details, claims about both climate benefits and agricultural co-benefits may become overstated or misleading.
The perspective also notes that soil context matters. Degraded or tropical soils may show stronger responses to biochar application than productive temperate soils, while activation strategies such as composting, fertilizer blending, or microbial inoculation may help enhance the soil benefits of more stable biochars.
The authors call for a “designer biochar” approach, in which products are tailored to specific end uses rather than marketed as universally beneficial. As biochar carbon credits continue to expand, transparent reporting and realistic claims will be vital to maintain trust and avoid misallocation of climate resources.
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Journal Reference: Brown, R.W., Chadwick, D.R. & Jones, D.L. Clarifying the conflation of biochar carbon stability and its soil co-benefits. Biochar 8, 67 (2026).
https://doi.org/10.1007/s42773-026-00581-4
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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.
Follow us on Facebook, X, and Bluesky.
Journal
Biochar
Method of Research
News article
Article Title
Clarifying the conflation of biochar carbon stability and its soil co-benefits
Soil scientist awarded $1.6 million NSF grant to study ‘living skin’ of arid ecosystems
Estelle Couradeau, College of Agricultural Sciences, receives NSF’s most prestigious award for early-career faculty to uncover the fate of the biocrust microbiome under growing temperature fluctuations
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Estelle Couradeau, Penn State assistant professor of soils and environmental microbiology, right, and two former members of her research group, postdoctoral scholar Raul Roman and lab technician Haneen Omari, sampling biocrust in New Mexico.
view moreCredit: Penn State
UNIVERSITY PARK, Pa. — A Penn State soil scientist has received a $1.6 million, five-year grant from the U.S. National Science Foundation (NSF) to fund her team’s study of how increasing temperature fluctuations impact the biocrust microbiome — the complex, thin-layer microbe community that stabilizes soil, fixes nitrogen and drives nutrient cycling in drylands.
Estelle Couradeau, assistant professor of soils and environmental microbiology in the College of Agricultural Sciences, is the recipient of the award from NSF’s Faculty Early Career Development Program (CAREER). She said she is extremely grateful for the opportunity to expand her team’s study of what she called the “living skin” of arid ecosystems and emphasized the importance of the research, which will officially begin in August.
Rapid changes in environmental conditions make it increasingly important to safeguard biocrusts, which are dominated by cyanobacteria, lichens, mosses and algae, and enhance their establishment in arid lands, Couradeau noted.
“Recent studies have indicated that current patterns of temperature variations drive more species loss than the fact that average temperatures are overall increasing,” she said. “In this project, I will ask, ‘how do biocrust microbes acclimate or adapt to thermal fluctuations?’ Answering this question will help predict biocrust thermal fluctuations under present and future climate conditions, with implications for biocrust inoculant production and biocrust-covered land management and restoration.”
Every minute, up to 57 acres of vegetated land are lost to desert due to aridification — the transition from a wetter to a drier climate — according to Couradeau, and 70% of dryland soils are currently degraded. The lack of restoration of these lands will put about 1 billion people at risk in the coming decades, she added.
“These microbially built soils in arid lands are the pioneer soils, sustaining the productivity and resiliency of these systems,” Couradeau said. “It is estimated that their coverage will decline by 25% to 40% within 60 years, reducing the ecosystem services they render proportionally, including soil stability and fertility. That has implications for global carbon, nitrogen cycles, the amount of dust in the air and human health.”
The research project will include a number of novel components, Couradeau said.
First, to learn how biocrust microbiomes will be affected by increased temperature fluctuations and gain a functional understanding of the associated shift in microbes’ metabolisms, Couradeau and her team will conduct experiments to determine the “tipping point” of temperature fluctuations for the biocrust system. The researchers will perform mesocosm experiments — using mason jars to create controlled thermal cycles and follow biocrust microbiome response using a combination of activity analysis and genetic sequencing.
Insights gained from this experiment, Couradeau explained, will be used by the researchers to mine the BIODESERT global survey dataset — which is led by the European Research Council — to see if comparable trends can be observed in biocrusts around the world, spanning a large set of latitudes and daily thermal ranges.
Second, the researchers will measure the physiological and behavioral response of the biocrust keystone cyanobacteria called Microcoleus to temperature fluctuations using SoilChips — transparent devices used by scientists to study the hidden world of soil microorganisms in real-time. Developed by project collaborator Edith Hammer, an associate professor at Lund University in Sweden, these microfluidic chips act as a window into the world of soil microbes.
Couradeau plans to use these thin chambers colonized by microbes to directly observe them, measuring with microscopic evaluation their metabolic tradeoffs between thermal adaptation and other cellular functions.
Third, Couradeau — in collaboration with Sarah Bordenstein, associate research professor in Penn State’s Eberly College of Science — will incorporate SoilChips and cyanobacteria behavior into science education. The researchers will introduce biocrust as a model system for soil science education by guiding students to create experiments utilizing SoilChips. They will conduct a pilot program with four partner high schools spanning arid and semi-arid regions of the western United States.
That educational activity, which includes publishing a curriculum building around SoilChip science, will include a citizen-science benefit as the classes’ work will provide more biocrust data for researchers to screen for cyanobacterial behavior.
Finally, in another creative component that Couradeau called “Breaking Ground,” the team will develop an online gallery of portraits of biocrust scientists to showcase their expertise. It will consolidate the biocrust research community to promote role models and career awareness in soil science, Couradeau explained, and provide teachers and instructors with a ready-to-use resource to broaden soil science curriculum in the classroom.
Other major collaborators on the project are Fernando Maestre, professor, KAUST, Saudi Arabia; Daniel Shay, high-school teacher at North Central High School in Spokane, Washington; Crystal Davis, high school teacher at California Academy of Mathematics and Science in Carson, California; Miranda Thornton, High-teacher at Basha High-School in Chandler, Arizona; Mary Ann Rall, teacher at Torrey Pines High School in San Diego, California; Anita Antoninka, assistant research professor, Northern Arizona University; Sonia Chamizo, postdoctoral scholar, University of Almeria, Spain; Yolanda Canton, professor, University of Almeria, Spain; Sasha Reed, researcher, U.S. Geological Survey, Utah; Miriam Munoz Rojas, research investigator and senior lecturer, University of Sevilla, Spain and University of New South Wales, Australia; Nicole Pietrasiak, associate professor, University of Las Vegas; Kristina Young, adjunct assistant professor, College of Natural Resources, Utah State University; and Ferran Garcia-Pichel, professor, Arizona State University.
A drylands soil sample showing biocrust filaments — microscopic, sticky threads produced by cyanobacteria that weave together to form a "living skin" on the surface of arid soils.
Credit
Penn State
Research shows plants such as canola, tomatoes and rice reduce iron uptake when stressed by drought
Study could also have implications for global food security and human nutrition
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PhD student Oluwadamilola Elizabeth Ajayi, left, and Dr. Connor Fitzpatrick, PhD, lead author on the study and now an assistant professor in the Department of Biological Sciences with UCalgary’s Faculty of Science.
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Credit: Colette Derworiz, Faculty of Science/University of Calgary
New research by scientists at the University of Calgary has found that plants, ranging from canola to rice to tomatoes, actively shut down their own ability to take up iron when they experience drought.
It’s a finding that could have implications for the nutritional value of agricultural crops.
The study, published in the journal Cell, questions whether plants send out a "cry for help" when they are stressed by drought to recruit beneficial soil microbes (e.g., bacteria and fungi) in their roots.
“We found that this shift is the result of specific changes to plant roots,” says Dr. Connor Fitzpatrick, PhD, lead author on the study and now an assistant professor in the Department of Biological Sciences with UCalgary’s Faculty of Science. “It happens because plants, under drought stress, dial down both their immune systems and their iron uptake machinery.”
Fitzpatrick says that allows a particular group of bacteria, called Streptomyces, to thrive — but it doesn’t automatically mean healthier plants. Some Streptomyces strains help, he explains, while others interfere.
“Together, this leads to a new way of thinking about plant-microbe interactions during drought,” he says. “Drought doesn’t just stress plants. It fundamentally rewires how they manage nutrients and interact with the microbial world around them.”
Fitzpatrick says the research is important for plant biology, but also provides insight into global food security and human nutrition.
“Iron deficiency is already one of the most widespread nutritional disorders in the world, affecting billions of people,” he says. “Much of the iron in human diets comes from plants such as cereals and legumes.
“At the same time, drought is increasing in frequency and severity across many agricultural regions due to climate change.”
Fitzpatrick, who did his postdoctoral work at the University of North Carolina at Chapel Hill and finished the research at UCalgary, says the research suggests the challenges could be more connected than previously appreciated.
“It means drought may not only reduce crop yield, but also reduce the nutritional quality of crops by limiting iron in edible tissues," he says.
Fitzpatrick says the research team found the reduction in iron uptake as they were trying to understand microbial enrichment in plant roots.
“We experimentally manipulated drought stress and iron availability to get at the mechanism,” he explains.
The team initially used a model organism, Arabidopsis thaliana, known as the fruit fly of the plant world, and later demonstrated it across a wide variety of plants.
“We’ve shown this for rice, we’ve shown this for tomato and, more recently, we’ve shown this for canola,” Fitzpatrick says.
The research opens the door to creating probiotic soil treatments or ways of breeding crops that sustain iron uptake during a drought, he adds.
Journal
Cell
Method of Research
Experimental study
Article Title
Streptomyces enrichment in roots during drought is uncoupled from plant benefit and is driven by host suppression of iron uptake and immunity
Article Publication Date
28-May-2026
