Energy use, carbon footprint and economic performance of rice production under different straw-returning systems and water-nitrogen management

Straw return is an important practice for improving soil fertility and promoting nutrient recycling in paddy fields. However, the integrated effects of different preceding crop straw incorporation patterns and their associated water and nitrogen management strategies on energy use, environmental performance, and economic benefits in rice production systems remain unclear. A field experiment was conducted under three crop rotation systems: rapeseed–rice (RR), wheat–rice (W R ), and cabbage–rice (CR), combined with conventional flooding (W0) or alternate wetting and drying (W1), and conventional nitrogen application (N1) or precision nitrogen reduction (N2). Rice yield, energy use, IPCC-estimated greenhouse gas emissions, carbon footprint (CF), and economic benefits were evaluated, and a membership function method was used for comprehensive assessment. Compared with CR, RR increased rice yield, energy use efficiency (EUE), and net return (NR) by 14.67%, 20.06%, and 58.83%, respectively, although CH 4 emissions were also higher. Compared with W0, W1 reduced energy input, CH 4 emissions, and CF, with CF decreasing by 15.87%–22.83%, while increasing rice yield and EUE. Compared with N1, N2 reduced N 2 O emissions, indirect CO 2 emissions, and non-renewable energy consumption without significantly affecting yield or NR. Comprehensive evaluation showed that RRW1N2 achieved the highest overall score. Overall, under the background of returning rapeseed straw to the field, the synergistic implementation of alternate wetting and drying irrigation and precision nitrogen reduction effectively coordinates production, energy, environmental, and economic benefits, thereby promoting the sustainability of rice production systems. Given the IPCC-based GHG estimates and single-region experiment, further validation is needed to confirm its broader applicability.