Controlled irrigation and drainage of a rice paddy field reduced global warming potential of its gas emissions.

摘要

The effect of controlled drainage on methane (CH₄) and nitrous oxide (N₂O) emissions from a paddy field under controlled irrigation (CI) was investigated by controlling the sub-surface drainage percolation rate with a lysimeter. CI technology is one of the major water-saving irrigation methods for rice growing in China. Water percolation rates were adjusted to three values (2, 5, and 8 mm d-1) in the study. On the one hand, the CH₄ emission flux and total CH₄ emission from paddy fields under CI decreased with the increase of percolation rates. Total CH₄ emissions during the growth stage of rice were 1.83, 1.16, and 1.05 g m-2 in the 2, 5, and 8 mm d-1 plots, respectively. On the other hand, the N₂O emission flux and total N₂O emissions from paddy fields under CI increased with the increase of percolation rates. Total N₂O emissions during the growth stage of rice were 0.304, 0.367, and 0.480 g m-2 in the 2, 5, and 8 mm d-1 plots, respectively. The seasonal carbon dioxide (CO₂) equivalent of CH₄ and N₂O emissions from paddy fields under CI was lowest in the 2 mm d-1 plot (1364 kg CO₂ ha-1). This value was 1.4% and 19.4% lower compared with that in the 5 and 8 mm d-1 plots, respectively. The joint application of CI and controlled drainage may be an effective mitigation strategy for reducing the carbon dioxide equivalents of CH₄ and N₂O emissions from paddy fields.