Effects of Water–Nitrogen Interaction Coupled with Straw Addition on Rice Paddy Field Grain Yield and Greenhouse Gas Emissions

This study was aimed to clarify the effects of the interaction between water and nitrogen on grain yield and greenhouse gases (GHGs) emissions under straw incorporation (SI) in a rice paddy field in northeast China. Under standard local rice paddy fields conditions, a split-plot design was used, with continuous flooding (CF) irrigation and alternate wetting and drying (AWD) irrigation as primary plot treatments, and traditional nitrogen application management (TNAM, basal fertilizer:tiller fertilizer:panicle fertilizer:spikelet fertilizer, 6:3:1:0), postponed nitrogen topdressing management 1 (PNTM1, basal fertilizer:tiller fertilizer:panicle fertilizer:spikelet fertilizer, 5:2:2:1), and postponed nitrogen topdressing management 2 (PNTM2, basal fertilizer:tiller fertilizer:panicle fertilizer:spikelet fertilizer, 4:3:2:1) as secondary plot treatments. The cumulative GHGs emissions, global warming potential (GWP), and grain yield at each reproductive stage under interactions between water and nitrogen were examined. Compared with CF, the grain yield of AWD in 2018 and 2019 increased significantly by 8.84% and 9.93%, respectively. There was no significant difference in grain yield between different nitrogen management practices under the same irrigation pattern. Compared with CF, AWD reduced CO2 and CH4 emissions by 27.82% and 47.96%, increased N2O emissions by 18.78%, and reduced the GWP and greenhouse gas intensity (GHGI) by 38.27% and 44.18%. Under AWD, there were no significant differences in CH4 emissions and GHGI between different nitrogen management treatments, and PNTM1 and PNTM2 significantly reduced CO2 emissions by 36.55% and 22.99%, increased N2O emissions by 70.59% and 76.47%, and significantly reduced GWP by 29.51% and 19.73%, respectively. Compared to TNAM, with PNTM1 achieving better emission reduction than PNTM2. Thus, AWD with PNTM1 under SI had the most significant abatement effect with stable grain yields. Thus, emission reductions can be achieved through utilizing the interaction between water and nitrogen under SI to ensure sustainable rice production in agricultural areas like those of central Jilin province.