Rice feeds more than half of the world's population, but producing it often requires large amounts of water and nitrogen fertilizer. Conventional flooded rice fields can support stable yields, yet they also place heavy pressure on water resources and contribute to ammonia emissions from agriculture. A new two-year field study published in Biochar suggests that a combined strategy using alternate wetting and drying irrigation and nitrogen-loaded biochar may offer a practical path toward more sustainable rice production.
Researchers tested the approach in paddy fields in Northeast China, comparing conventional continuous flooding with alternate wetting and drying, known as AWD. They also evaluated the addition of nitrogen-loaded biochar, a straw-derived biochar engineered to hold ammonium nitrogen and release it more gradually in soil.
The results point to a promising "triple win." Compared with continuous flooding, AWD alone reduced water use by 14.17 to 15.56 percent while increasing rice yield by 2.23 to 5.11 percent. When nitrogen-loaded biochar was added under AWD, rice yields increased further by 6.70 to 12.55 percent, while water use dropped by another 6.81 to 12.37 percent compared with AWD without biochar.
"Rice production is facing a difficult balance between feeding people, saving water, and reducing environmental impacts," said corresponding author Guangyan Liu of Shenyang Agricultural University. "Our study shows that these goals do not have to compete with each other. By pairing smarter irrigation with nitrogen-loaded biochar, farmers may be able to improve yield while using less water and reducing nitrogen losses."
A major concern in nitrogen-intensive rice farming is ammonia volatilization, a pathway by which nitrogen escapes from soil into the atmosphere. The study found that nitrogen-loaded biochar alone could increase ammonia volatilization under continuously flooded conditions, likely because it added a concentrated nitrogen source. However, this risk was greatly reduced when biochar was combined with AWD. Under AWD, the biochar-supported system consistently maintained lower ammonia loss than continuously flooded systems with biochar.
The researchers suggest that the synergy comes from two complementary mechanisms. AWD creates cycles of wetting and drying that can improve root activity and soil nitrogen dynamics, but it may also make nitrogen availability less predictable. Nitrogen-loaded biochar helps buffer this instability by retaining ammonium in its pore structure and releasing nitrogen in a more controlled way. At the same time, the biochar can improve soil water retention during drying periods, supporting plants when water is limited.
Using partial least squares path modeling, the team found that both AWD and nitrogen-loaded biochar directly improved rice nitrogen accumulation and reduced water consumption, contributing to yield gains. AWD also directly reduced ammonia volatilization and positively influenced yield.
"These findings provide a scalable framework for rice systems under increasing climate and resource pressures," said corresponding author Qi Wu. "The combination of AWD and nitrogen-loaded biochar can help align rice production with the goals of food security, clean water, and climate action."
The study highlights a next-generation management strategy for rice farming, especially in regions where water scarcity and nitrogen loss are growing concerns. While further work is needed to evaluate long-term field performance, economic feasibility, and site-specific recommendations, the findings show that integrated water and nitrogen management can move rice production beyond trade-offs and toward shared benefits for farmers and the environment.
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Journal Reference: Chen, H., Liu, G., Sun, Y. et al. Closing the rice production trilemma: AWD and nitrogen-loaded biochar synergy achieves co-benefits in yield improvement, water saving, and ammonia mitigation. Biochar 8, 79 (2026).
https://doi.org/10.1007/s42773-026-00602-2
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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.
