Effect of Water Management on Greenhouse Gas Emissions from Rice Paddies Using a Slow-release Fertilizer

Methane (CH 4 ) and nitrous oxide (N 2 O) are significant contributors to greenhouse gas (GHG) emissions from rice fields. Mid-summer drainage is a commonly practiced water management technique that reduces CH 4 emissions from rice fields. Slow-release fertilizers gradually release nutrients over an extended period and have been shown to reduce N 2 O emissions. However, the combined effect of slow-release fertilizer and water management on GHG emissions remains unclear. This study compared GHG emissions from a rice paddy subjected to mid-summer drainage for 10 days (control) with that of a rice paddy subjected to prolonged mid-summer drainage for 20 days combined with slow-release fertilizer (W+S). Gas sampling was conducted weekly using a closed chamber method. During the rice cultivation period, cumulative CH 4 and N 2 O emissions were reduced by 12.3% and 16.2%, respectively, in the W+S treatment compared to the control. Moreover, the W+S treatment exhibited a 1.9% increase in grain yield compared to the control. Under experimental conditions, slow-release fertilizers, in combination with prolonged mid-summer drainage, proved to be the optimal approach for achieving high crop yield while reducing GHG emissions. This represents an effective strategy to mitigate GHG emissions from rice paddy fields.