New irrigation management in paddy fields reduces methane emissions and increases water use efficiency

Area of Science:

• Agricultural Science
• Environmental Science
• Agronomy

Background:

• Effective water management in rice cultivation is vital for optimizing crop yield, water use efficiency (WUE), and mitigating greenhouse gas (GHG) emissions.
• Subtropical paddy rice systems face challenges in balancing productivity with environmental sustainability.

Purpose of the Study:

• To evaluate the impact of different water management systems on rice yield, WUE, and GHG emissions in a subtropical paddy rice field.
• To compare continuous flooding (CF) with intermittent flooding (IF) and saturated soil (SS) systems.

Main Methods:

• A three-year field experiment was conducted using three water management systems: continuous flooding (CF), intermittent flooding (IF), and saturated soil (SS).
• Agronomic data (rice yield) and environmental parameters (water consumption, N2O and CH4 emissions) were monitored over three growing seasons.
• Greenhouse gas emission intensity was calculated as GHG emissions per unit of rice yield (YpGWP).

Main Results:

• Compared to CF, IF and SS systems reduced water consumption by 18% and 30%, respectively.
• Seasonal CH4 emissions were reduced by an average of 58% in IF and SS systems compared to CF.
• The SS and IF systems decreased overall GHG emissions by 63% and 48%, respectively, with a ~50% reduction in global warming potential.
• Rice yield was reduced by 9% in the SS system compared to CF.

Conclusions:

• Intermittent flooding (IF) and saturated soil (SS) water management strategies offer substantial reductions in water use and GHG emissions in subtropical rice cultivation.
• A key challenge for wider adoption of these water-saving irrigation techniques is the associated reduction in rice yield.
• Further research and development are needed to optimize water management practices to maintain rice productivity while maximizing environmental benefits.