A growing body of research suggests that integrating aquatic animals into rice farming could significantly improve nitrogen efficiency while reducing environmental pollution. A new review synthesizes recent scientific findings and proposes that activity at the soil–water interface is the critical engine driving these benefits.
Nitrogen fertilizer is essential for global food production, yet only about half of applied nitrogen is absorbed by crops. The remainder is lost through runoff, volatilization, or conversion to greenhouse gases, contributing to water pollution, climate change, and higher farming costs. Improving nitrogen efficiency is therefore a major goal for sustainable agriculture.
The review examines rice–aquatic animal co-culture systems, in which rice is grown alongside fish, shrimp, crabs, or other aquatic organisms. These systems, practiced for centuries in parts of Asia, are gaining renewed interest as nature-based agricultural solutions.
According to the authors, the key to their effectiveness lies in the dynamic interactions between rice roots, aquatic animals, and microorganisms at the soil–water interface.
"Our synthesis shows that the interface between soil and floodwater is not just a boundary, but a highly active regulatory zone controlling nitrogen cycling," said the study's corresponding author. "When plants, animals, and microbes interact there, they create conditions that enhance nutrient recycling and reduce losses."
The review identifies three main mechanisms behind these improvements.
First, physical disturbance caused by aquatic animals plays an important role. Their movement and burrowing mix sediments, increase oxygen exchange, and accelerate nutrient transport. This process, known as bioturbation, reduces stagnant zones and enhances chemical reactions that transform nitrogen into forms usable by plants.
Second, rice roots themselves modify their surroundings. Oxygen released by roots creates micro-scale oxidized zones, while organic compounds from roots provide energy sources for microbes. Together, these factors help maintain a balance between nitrogen oxidation and reduction processes.
Third, microbial communities flourish in these dynamic environments. Different groups of bacteria cooperate to convert nitrogen among various forms, allowing the system to recycle nutrients efficiently instead of losing them to the atmosphere or waterways.
The authors report that properly managed co-culture systems can increase nitrogen-use efficiency by roughly 20 to 40 percent while lowering greenhouse gas emissions and fertilizer requirements. These benefits arise because nitrogen is retained within plants, sediments, and microbial biomass rather than escaping into the environment.
"This is essentially a self-reinforcing loop," the authors noted. "Animal disturbance, plant processes, and microbial metabolism work together to create a more closed nitrogen cycle."
The review also highlights that system performance depends strongly on management choices such as water levels, animal density, and fertilizer inputs. While the ecological benefits are promising, the authors emphasize that more long-term field studies and standardized measurements are needed to fully quantify impacts across different climates and farming systems.
Looking ahead, the researchers argue that future studies should combine advanced monitoring technologies, microbial analyses, and ecosystem modeling to better understand how these systems function at fine spatial scales.
As the global population grows and environmental pressures intensify, integrated farming strategies may offer a path toward producing food more efficiently while reducing ecological damage.
"Rice–aquatic co-culture systems show how traditional agricultural practices can inspire modern sustainability solutions," the authors concluded. "By working with natural processes rather than against them, agriculture can become both productive and environmentally responsible."
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Journal Reference: Li K, Qin C, Pang Z, Liu Z, Zhou J, et al. 2026. Promotion of nitrogen accumulation through enhanced soil-water interface activity in rice-aquatic animal co-culture systems: a review. Nitrogen Cycling 2: e007 doi: 10.48130/nc-0025-0019
https://www.maxapress.com/article/doi/10.48130/nc-0025-0019
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Nitrogen Cycling (e-ISSN 3069-8111) is a multidisciplinary platform for communicating advances in fundamental and applied research on the nitrogen cycle. It is dedicated to serving as an innovative, efficient, and professional platform for researchers in the field of nitrogen cycling worldwide to deliver findings from this rapidly expanding field of science.
