The researchers found that the combined treatment reduced cumulative ammonia volatilization by 27.1 percent compared with conventional urea fertilization during a complete rice-wheat rotation. The result is particularly notable because the amended organic fertilizer was applied with a 30 percent reduction in mineral nitrogen input, yet crop productivity was largely maintained. The findings point toward a potential strategy for making fertilizer use more efficient without simply asking farmers to apply less and accept lower yields. Instead, the approach aims to control what happens to nitrogen after it enters the soil.

“Reducing fertilizer input is only useful if farmers can maintain crop production at the same time,” said corresponding author Haijun Sun. “Our results suggest that combining biochar with dicyandiamide in organic fertilizer can help balance these goals by retaining nitrogen, limiting ammonia losses, and supporting crop growth.” That balance is central to the global fertilizer challenge. Nitrogen is indispensable for plant proteins, chlorophyll, and growth, but when it is converted into gaseous ammonia and lost from farmland, farmers may need to spend more on replacement fertilizer while nearby communities and ecosystems absorb the pollution.

The experiment covered two complete rice and wheat rotations from 2022 to 2024 in greenhouse soil columns. The researchers compared conventional urea fertilization with three treatments that used lower amounts of mineral nitrogen: conventional organic fertilizer, organic fertilizer amended with biochar, and organic fertilizer containing both biochar and dicyandiamide. The soil-column design allowed the team to monitor nitrogen movement and ammonia emissions under controlled conditions over successive crop seasons. Unlike a short laboratory test, the two-year rotation captured repeated changes in soil chemistry, crop uptake, and fertilizer behavior across both flooded rice and relatively dry wheat production.

Among the treatments, the combination of biochar and dicyandiamide produced the most consistent result. Across the full rotation, it was the only organic fertilizer treatment that significantly reduced cumulative ammonia emissions compared with conventional urea. Biochar alone reduced cumulative ammonia volatilization by 5.9 percent compared with conventional organic fertilizer, while adding both biochar and dicyandiamide achieved a much larger 33.6 percent reduction relative to that treatment. These results suggest that the two amendments may work through complementary mechanisms rather than simply adding the same effect twice.

Biochar is a carbon-rich material produced by heating biomass under oxygen-limited conditions. Its porous structure can alter soil water retention, nutrient adsorption, and the chemical environment surrounding fertilizer particles. In this study, the researchers linked biochar application to better regulation of ammonium concentrations and pH in the soil and the floodwater covering rice. This matters because ammonia volatilization is strongly influenced by the balance between ammonium ions and dissolved ammonia. Higher pH shifts more ammonium toward gaseous ammonia, making it easier for nitrogen to escape. By moderating this chemical environment, biochar may help keep nitrogen in a less volatile form for longer.

Dicyandiamide, commonly known as DCD, is a nitrification inhibitor that slows the microbial conversion of ammonium into nitrite and nitrate. That process can be beneficial under some conditions because plants can absorb nitrate, but rapid nitrification can also increase the risk of nitrogen leaching and nitrous oxide production. By delaying the transformation, DCD may extend the period during which ammonium remains available for plant uptake or retention in the soil. The researchers observed altered nitrogen transformation patterns in the amended treatment, indicating that the inhibitor helped reshape the timing and pathways of nitrogen cycling rather than merely reducing one isolated emission.

The study also examined soil bacteria and found that biochar-containing fertilizers reduced the abundance of Nitrospirota, a bacterial group associated with nitrite oxidation, one of the key steps in nitrification. The shift suggests that the amendments may change the microbial niches involved in nitrogen conversion by modifying factors such as pH, moisture, carbon availability, and nutrient distribution. However, the researchers emphasize that their microbial analysis was based on taxonomic profiling. Detecting changes in the abundance of a bacterial group does not directly prove that a particular organism performed a specific biochemical function, so future work using functional genes, enzyme measurements, and isotope tracing will be needed to confirm the mechanisms.

The environmental gains did not appear to come at the expense of another major greenhouse gas. Cumulative nitrous oxide emissions showed no significant differences among the fertilizer treatments, an important finding because strategies that suppress ammonia can sometimes redirect nitrogen losses into other pathways. The combined treatment also maintained rice yields at levels comparable with conventional fertilization, while conventional organic fertilizer and biochar-only organic fertilizer reduced rice grain yields. The researchers estimated through Monte Carlo simulations that the combined treatment could generate potential benefits of approximately 36,600 Chinese yuan per hectare per year under the experimental conditions, reflecting fertilizer savings and reduced nitrogen-related environmental and health costs.

The result is promising, but it is not yet a universal prescription for farmers. The experiment was conducted in controlled soil columns rather than commercial fields, where rainfall, temperature swings, soil types, irrigation practices, fertilizer placement, and management decisions can vary dramatically. The economic estimate also depends on local fertilizer prices, crop yields, pollution costs, and the availability and quality of biochar and dicyandiamide. Field-scale trials will be essential to determine whether the ammonia reductions persist under real farming conditions and whether the treatment remains affordable and practical across different rice-wheat systems. Even with those limitations, the study offers a striking example of how combining carbon-based soil amendments with targeted nitrogen management could help turn fertilizer from a major source of pollution into a more efficient tool for feeding a growing population.

Subject of Research: Nitrogen fertilizer efficiency, ammonia volatilization, biochar, dicyandiamide, soil nitrogen cycling, and rice-wheat crop production

Article Title: Ammonia mitigation and economic gains from dicyandiamide and biochar-amended organic fertilizer: a 2-year rice-wheat rotation study

News Publication Date: 22-Jun-2026

Web References: https://doi.org/10.48130/aee-0026-0016; Agricultural Ecology and Environment

References: Huang W, Wang L, Gong X, Bian R, Lu X, et al. 2026. “Ammonia mitigation and economic gains from dicyandiamide and biochar-amended organic fertilizer: a 2-year rice-wheat rotation study.” Agricultural Ecology and Environment 2: e019. DOI: 10.48130/aee-0026-0016

Image Credits: Wang Huang, Lisha Wang, Xueliu Gong, Rongjun Bian, Xinyue Lu, Yuanqing Bu, Yunyi Liang, Haijun Sun, Yanfang Feng, Changlei Xia, Jiang Jiang, and Lihong Xue

Keywords: ammonia volatilization, biochar, dicyandiamide, organic fertilizer, nitrogen fertilizer, nitrogen cycling, rice-wheat rotation, soil microbiome, nitrification inhibition, sustainable agriculture, crop productivity, agricultural pollution

Professor Bates’ latest work, supported by a prestigious National Science Foundation CAREER Award amounting to $702,370, represents an innovative marriage of electrocatalysis and sustainable energy technologies. Electrocatalysis, the catalysis of chemical reactions at the electrode-electrolyte interface driven by an applied electric potential, offers a promising avenue for converting nitrate pollutants into useful compounds such as ammonia. Yet, the complexity of this electrochemical environment, where multiple competing reactions simultaneously occur, notoriously reduces conversion efficiency and yields unwanted by-products, thus complicating practical applications. Bates’ research aims to unravel these complexities by employing advanced catalytic design principles to optimize reaction selectivity and efficiency.

Catalysis engineering—the science behind tailoring catalysts to enhance specific chemical reactions—lies at the heart of Bates’ approach. In industrial settings, catalysis underpins the efficient production of fuels, chemicals, and materials, dramatically reducing cost, energy inputs, and environmental impacts. However, applying these principles to electrocatalytic nitrate conversion challenges conventional boundaries. Bates’ project proposes to engineer electrode materials that selectively drive nitrate reduction to ammonia with high efficiency, ideally powered by solar or wind-derived electricity. This on-site, modular approach could revolutionize nitrate remediation, transforming diffuse agricultural runoff from an environmental liability into a resource for producing ammonia, a key industrial precursor.

The broader environmental implications of this technology are compelling. Current nitrogen cycle disruptions—largely driven by excessive fertilizer use—have contributed to eutrophication, hypoxic zones, and biodiversity loss in aquatic ecosystems globally. A decentralized, renewable-powered nitrate-to-ammonia conversion technology could mitigate these effects by intercepting nitrates before they enter waterways, closing the loop in nitrogen management. Bates stresses the importance of not simply halting fertilizer use, which underpins global food security, but augmenting nature’s capacity to process and recycle nitrogen efficiently through innovative chemical engineering.

To overcome the hurdle of reaction pathway complexity, Bates integrates insights gained from thermal catalysis, an established field specializing in heterogeneous catalytic reactions at elevated temperatures and pressures. Unlike electrocatalysis, thermal catalytic processes have been extensively studied and optimized across industry. By adapting methodologies and conceptual frameworks from thermal catalysis—including kinetic modeling and reaction mechanism analysis—Bates hopes to pioneer novel strategies for dissecting and steering electrocatalytic nitrate reduction reactions at ambient conditions. This cross-disciplinary synergy exemplifies the evolving landscape of catalysis research.

Central to the experimental investigation is the deployment of modulation excitation spectroscopy (MES), a cutting-edge technique routinely harnessed in thermal catalysis but rarely applied to electrocatalytic systems. MES involves systematic modulation of an experimental parameter—in this case, electrical voltage or electrolyte composition—while monitoring the material’s response via spectroscopic probes. MES enables suppression of noise and enhancement of subtle spectral features associated with transient intermediates, allowing unprecedented insight into dynamic reaction processes on electrode surfaces. Graduate researcher Zayan Akmal spearheads this effort by applying MES to electrochemical flow cells, where catalysts experience a continuous flux of nitrate-containing electrolytes under controlled electric potential.

Bates elaborates that MES produces a temporal dataset akin to filming a reaction “movie” rather than capturing static “snapshots.” This dynamic perspective facilitates identification of reaction intermediates and elucidation of reaction pathways central to optimizing product selectivity. Such mechanistic understanding is crucial for rational catalyst design tailored to promote the most efficient and selective nitrate-to-ammonia transformation, thereby minimizing parasitic reactions and undesired byproducts.

Complementing MES studies, graduate student Isaac Boateng utilizes conventional electrochemical cells in conjunction with kinetic modeling inspired by thermal catalysis frameworks. This dual-pronged approach—combining state-of-the-art spectroscopic techniques with rigorous reaction kinetics—ensures a comprehensive understanding from atomic-scale surface interactions to macroscopic reaction rates. The integration of both electrocatalytic and thermal catalysis philosophies highlights the transformative nature of Bates’ research, which aims to deliver foundational science capable of underpinning scalable industrial technologies.

Beyond the laboratory, Bates’ vision extends to education and workforce development. Collaborating with the University of Virginia’s First-Year Engineering Center, he is expanding curriculum offerings in foundational design courses to include electrochemical water treatment systems. This pedagogical integration prepares a new generation of engineers to tackle complex environmental challenges with interdisciplinary tools. Additionally, starting in 2027, his lab will host paid summer research internships for local high school students through Charlottesville’s Community Attention Youth Internship Program, fostering early engagement and diversity in STEM fields.

The anticipated impact of this research transcends nitrate remediation. By advancing fundamental understanding of electrocatalytic mechanisms and integrating renewable energy into chemical synthesis, Bates’ work paves the way for decentralized manufacturing of numerous nitrogen-containing compounds and other value-added chemicals. This paradigm shift from centralized, high-temperature, high-pressure chemical plants to scalable, modular, renewable-powered devices promises to reduce industrial energy consumption, environmental footprint, and reliance on fossil fuels.

Reflecting on his broader aspirations, Bates emphasizes that the true legacy of such academic research lies in cultivating future innovators. “Our greatest impact isn’t published papers or the proposals that get funded,” he asserts, “it’s producing students who will go out in the world and develop these technologies.” Through rigorous research, innovative education programs, and community engagement, Bates exemplifies the role of engineering as a catalyst for transformative solutions to some of the world’s most pressing problems.

Subject of Research:
Electrocatalytic conversion of nitrate pollutants into valuable chemical products using renewable electricity.

Article Title:
Advancing Electrocatalytic Technologies for Sustainable Nitrate Conversion into Ammonia

News Publication Date:
Not specified

Web References:
[1] Jason Bates, University of Virginia Faculty Profile – https://engineering.virginia.edu/faculty/jason-bates
[2] National Science Foundation CAREER Program – https://www.nsf.gov/funding/opportunities/career-faculty-early-career-development-program
[3] UVA Catalysis Initiative for Clean Energy and Chemicals – https://catalysis.research.virginia.edu/
[4] UVA First-Year Engineering Center – https://engineering.virginia.edu/offices-programs/first-year-engineering
[5] Charlottesville Community Attention Youth Internship Program – https://www.charlottesville.gov/256/Community-Attention-Youth-Internship

Image Credits:
Matt Cosner, University of Virginia School of Engineering and Applied Science

Keywords:
Electrocatalysis, nitrate reduction, sustainable chemistry, ammonia synthesis, renewable energy, catalysis engineering, modulation excitation spectroscopy, water treatment, nitrogen cycle, chemical engineering education, solar-powered catalysis, environmental remediation