A rice field that supports fish, ducks, and a floating green mat of Azolla may appear unconventional, but a two-year field study by the Tamil Nadu Rice Research Institute (TRRI), Aduthurai, suggests that such integrated farming could offer a practical response to climate change in paddy cultivation. The approach not only reduced greenhouse gas emissions significantly but also delivered a sharp increase in grain yield.
The study was conducted during the 2022–23 and 2023–24 samba seasons and compared conventional rice monoculture with an integrated farming system that combines biological inputs and multiple farm components.
Greenhouse gas footprint reduced by nearly one third
Researchers found that the integrated rice farming system reduced the overall climate change impact, measured in carbon dioxide equivalent, by 32.6 percent compared with conventional paddy cultivation that relies heavily on chemical fertilisers.
Paddy farming is a major contributor to agricultural greenhouse gas emissions because flooded fields create oxygen-deficient conditions that promote methane production, while excessive fertiliser use increases nitrous oxide emissions. Both gases trap significantly more heat than carbon dioxide.
Methane and nitrous oxide emissions drop sharply
In the integrated plots, rice was grown after a green manure crop, daincha, and supported with beneficial microbes such as phosphorus-, potassium-, and zinc-solubilising bacteria. Fish rearing, duck foraging, and dual cropping of Azolla were introduced as complementary elements.
These interventions altered the soil and water environment in ways that improved nutrient recycling and weakened conditions favourable for methane-producing microbes. Measurements showed a 34.2 percent reduction in methane emissions and a 24.9 percent reduction in nitrous oxide emissions compared with chemically fertilised fields.
Although carbon dioxide emissions increased due to higher biological activity and organic matter decomposition, researchers noted that the overall warming potential still declined because methane and nitrous oxide have a much stronger heat-trapping effect over comparable timeframes.
Yield rises by forty five percent despite lower chemical inputs
Alongside emission reductions, grain yield increased by about 45 percent under the integrated system. According to the researchers, improved soil health, enhanced microbial activity, and better nutrient availability contributed to higher productivity.
K Subrahmaniyan, Director of TRRI, said the findings challenge conventional definitions of productivity in paddy cultivation. He noted that integrated farming should be viewed not only through the lens of yield, but also food security, nutrition, and long-term soil health.
“When multiple components are integrated with paddy, the same land produces more value,” he said. “Fish becomes a source of protein and additional income, alongside the crop.”
Model designed to work for small farmers
Importantly, the researchers stressed that the system is viable even for small and marginal farmers. On a one-acre farm, dedicating around 10 percent of the land to a peripheral trench, roughly one metre wide and one metre deep, could cost about ten thousand rupees.
Under proper management, such a setup can produce up to four hundred kilograms of fish, generating an estimated additional income of twenty five thousand rupees, apart from earnings from rice cultivation. In this layout, about ninety cents remains under paddy while ten cents supports fish, with ducks integrated in some versions.
The TRRI study suggests that integrated rice farming offers a climate-smart pathway that balances productivity with environmental responsibility. By reducing methane and nitrous oxide emissions while improving yields and farm income, the model demonstrates how biological diversity and traditional farming wisdom can play a central role in adapting agriculture to a warming world.