Water-saving irrigation practices reduces greenhouse gas emission
intensity in double rice-cropping systems in the Southern China
Abstract
The development of water-saving irrigation strategies is crucial because
of the increasing demand on water resources. There is a need to improve
our understanding of water use strategies that save water and reduce
greenhouse gas (GHG) emissions without causing yield losses in paddy
soil. The current study was carried out to examine the net global
warming potential (NGWP) and net greenhouse gas intensity (NGHGI) based
on net GHG emissions calculations, including soil organic carbon (SOC)
change and indirect emissions (IE). The experiment was carried out under
flood irrigation (FI), shallow irrigation (SI), and intermittent
irrigation (II) conditions. The results showed that average double rice
yields under SI and II were significantly higher than those under FI by
4.5% and 12.2%, respectively, but without significantly difference at
annual mean SOC sequestration rate (0-30 cm) over 2 years among the
three irrigation regimes. Compared to FI, the annual methane (CH4)
emissions decreased by 34% and 45% under SI and II irrigation regimes,
respectively. In contrast, nitrous oxide (N2O) emissions under the SI
and II increased by 27% and 50%, respectively. IE were nearly the same
among the three irrigation regimes, with fertilizer use as the top
contributor, and followed the order FI > SI >
II. The NGWP and NGHGI respectively decreased by 40% and 45% under II
compared to those under FI. In conclusion, water-saving irrigation
strategies, especially the II practice, are an effective choice that can
simultaneously achieve great success in saving water, increasing rice
production, and reducing GHG emissions.