Alternate wetting and drying maintains rice yield and reduces global warming potential: A global meta-analysis

Context: Rice production systems are significant sources of anthropogenic emissions of the greenhouse gases (GHGs) i.e., methane (CH4) 4 ) and nitrous oxide (N2O). 2 O). Practicing alternate wetting and drying (AWD) in rice substantially affects rice yield as well as CH4 4 and N2O 2 O emissions from rice fields. However, it is difficult to determine global impacts from individual experiments as these studies differ in practice, experimental design, locations, nature of soil, and agro-ecological regions. Objective: The objectives of this article include (i) to conduct a global and comprehensive analysis to clarify the effects of AWD on rice yield, GHGs emissions, global warming potential (GWP), and greenhouse gas emission intensity (GHGI) in the context of a variety of climatic conditions and initial soil properties, and (ii) to explore the effects of different agronomic measures on rice yield and emissions of GHGs under AWD. Method: In this study, we analyzed 72 peer-reviewed studies worldwide that provide insights into the effects of climate, initial soil conditions, and agricultural management practices on rice yields, GHGs, GWP, and GHGI under AWD conditions. Results: The results found that AWD led to 1.52 % increase in rice yield with a 42.59 % increase in N2O 2 O emissions, however, CH4, 4 , GWP, and GHGI were reduced by 43.23 %, 36.84 %, and 38.57 %, respectively. Moreover, regional climatic factors and soil properties substantially affects the rice yield and GWP e.g., low mean annual temperature (<= <= 15degree celsius) and precipitation (<= <= 1000 mm) are conducive for emission reduction potential of CH4 4 and GWP. In addition, AWD reduced GWP highest in soils having pH <= 6.5, organic carbon content <= 12 g kg(-1), total nitrogen >= 2 g kg(-1), and high available N, P and K contents. Overall, rice yield improvements with decreased GHGs, GWP and GHGI were observed at 100-150 kg hm 2 N fertilizer application rate, and the use of enhanced- efficiency fertilizers, deep fertilization, and biochar application. Furthermore, AWD increased economic benefits and energy use efficiency through the reduction of costs and energy losses associated with irrigation. Conclusions: Thus, appropriate agronomic measures should be taken according to the local conditions for sustainable rice production with minimum emissions of GHGs.