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

Abstract

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.