In the heart of China’s agricultural landscape, an ancient practice is making a modern comeback, offering a promising solution to some of today’s most pressing environmental challenges. Rice and Azolla co-cultivation, a technique that dates back centuries, is gaining traction as a nature-based solution for reducing greenhouse gas emissions while maintaining, and even increasing, rice yields. This innovative approach has been the subject of a recent study published in *Agricultural Water Management*, led by Wei Yang of the Hubei Key Laboratory of Waterlogging Disaster and Agricultural Use of Wetland at Yangtze University.
The study, which employed a series of pot experiments with varying irrigation regimes, revealed that rice and Azolla co-cultivation can reduce methane (CH₄) emissions by 2.9% to 13.2%. This reduction is attributed to a decrease in the abundance of specific genes and enzymes, such as mcrA and β-1,4-glucanase, and an increase in others, like pmoA and Eh. “The reduction in CH₄ emissions is particularly significant under higher water depths, which are typically associated with increased emissions,” Yang explained. “This suggests that rice and Azolla co-cultivation could be a valuable strategy for mitigating emissions in water-intensive rice farming systems.”
Moreover, the study found that this co-cultivation method can decrease nitrous oxide (N₂O) emissions by 1.7% to 8.6%. Compared to alternate wetting and drying (AWD) irrigation, the 2 cm and 5 cm irrigation regimes reduced N₂O emissions by 22.0% to 39.7%. This reduction is linked to changes in the abundance of specific genes and enzymes, such as AOA, AOB, and nosZ. “The reduction in N₂O emissions is a significant finding, as N₂O is a potent greenhouse gas with a global warming potential 298 times that of CO₂,” Yang noted.
In addition to its environmental benefits, rice and Azolla co-cultivation also enhanced rice yield by 6.2% to 8.3% under all irrigation regimes. This increase in yield, combined with the reduction in greenhouse gas emissions, makes this co-cultivation method a promising strategy for low-carbon, high-yield rice farming.
The commercial implications of this research are substantial. As the global population continues to grow, so too does the demand for food. Rice, a staple food for more than half of the world’s population, is a critical component of global food security. By increasing rice yields while reducing greenhouse gas emissions, rice and Azolla co-cultivation could help meet this growing demand in a more sustainable and environmentally friendly manner.
Furthermore, this co-cultivation method could have significant implications for the agriculture sector’s transition towards low-carbon practices. As governments and industries worldwide strive to reduce their carbon footprints, innovative strategies like rice and Azolla co-cultivation could play a crucial role in achieving these goals.
Looking ahead, this research could pave the way for further developments in the field of nature-based solutions for agriculture. By harnessing the power of natural processes and ecosystems, farmers and researchers alike can work towards a more sustainable and resilient future for agriculture. As Yang put it, “This study is just the beginning. There is still much to learn about the potential of rice and Azolla co-cultivation, and we are excited to explore these possibilities in future research.”
In the meantime, the findings of this study offer a beacon of hope for a more sustainable future for rice farming, one that balances the need for increased food production with the imperative to protect our planet.