Securing food and energy supplies presents a significant challenge to human survival and progress. The rice-wheat rotation is one of the main food crop systems in China. However, no comprehensive assessment of the water footprint (WF), carbon footprint (CF), carbon production efficiency (CPE), and net ecosystem economic benefits (NEEB) of different rice-wheat rotation systems has been reported. This study was conducted to assess the productivity, WF, CF, CPE, and NEEB of dry direct-seeded, wet direct-seeded, and transplanted rice-wheat (TR-W) rotation systems. The objective was to provide theoretical guidance for the development of clean and sustainable rice-wheat rotation production technology systems. We used a split-plot design, with the main plots being the dry direct-seeded, wet direct-seeded, and transplanted rice planting methods, and the subplots consisting of two rice genotypes. Dry direct-seeded rice was mainly rainfed, ensuring that the soil remained relatively dry so that the soil is kept aerobic during the whole reproductive period of rice. Wet direct-seeded rice continues to keep the soil moist after sowing; the plots were maintained under a water layer of 3–10 cm following the emergence of 4.5 leaves, a condition that persisted until two weeks prior to the rice harvest. Transplanted rice was maintained under a water layer of 3–10 cm following transplanting until 2 weeks prior to the rice harvest. Subsequent to the rice harvest, the above-ground rice stubble was removed, and the ground was tilled with a rotary tiller in preparation for the subsequent wheat planting. Results demonstrated that the annual yield from the dry direct-seeded rice-wheat (DR-W) rotation system was comparable to the wet direct-seeded rice-wheat (W-W) rotation system, while significantly lower than that of the TR-W rotation system. However, the WF of DR-W rotation system was 45.96% and 33.94% lower than that of W-W and TR-W rotation systems, respectively, and the CF was 35.57% and 25.87% lower than that of W-W and TR-W rotation systems, respectively. Therefore, its water and carbon production efficiencies were higher than those of W-W and TR-W rotation systems. In addition, NEEB in DR-W and TR-W was comparable and significantly higher than that in W-W. The DR-W rotation was a promising rotation system according to the comparable annual yield, lower water and carbon footprints, higher CPE, and comparable or higher NEEB in comparison with other rice-wheat rotation systems. We suggest that the DR-W rotation should be promoted as the primary production mode for the rice-wheat rotation.

中文翻译：

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旱直播稻麦轮作系统：水足迹和碳足迹更低，碳生产效率和生态系统净经济效益更高

确保粮食和能源供应对人类生存和进步提出了重大挑战。稻麦轮作是我国主要粮食作物制度之一。然而，目前尚未有关于不同稻麦轮作系统的水足迹（WF）、碳足迹（CF）、碳生产效率（CPE）和净生态系统经济效益（NEEB）的综合评估报道。本研究旨在评估干直播、湿直播和移栽稻麦轮作系统的生产力、WF、CF、CPE 和 NEEB。目的是为开发清洁、可持续的稻麦轮作生产技术体系提供理论指导。我们采用裂区设计，主区为干直播、湿直播和移栽水稻种植方式，子区由两种水稻基因型组成。旱直播稻以雨养为主，保证土壤保持相对干燥，使水稻整个生育期土壤保持有氧。湿直播稻播种后继续保持土壤湿润；出现 4.5 片叶子后，地块保持在 3-10 厘米的水层下，这种情况一直持续到水稻收获前两周。移栽后的水稻保持在 3-10 厘米的水层下，直至水稻收获前 2 周。水稻收割后，将地上的稻茬清除，用旋耕机翻耕地面，为接下来的小麦播种做准备。结果表明，干直播稻麦（DR-W）轮作体系的年产量与湿直播稻麦（WW）轮作体系相当，但显着低于TR-W轮作体系系统。然而，DR-W旋转系统的WF分别比WW和TR-W旋转系统低45.96%和33.94%，CF比WW和TR-W旋转系统低35.57%和25.87% ， 分别。因此，其产水和产碳效率高于WW和TR-W轮转系统。此外，DR-W和TR-W的NEEB具有可比性，并且显着高于WW。与其他稻麦轮作系统相比，根据可比较的年产量、较低的水和碳足迹、较高的 CPE 以及可比较或较高的 NEEB，DR-W 轮作系统是一种很有前途的轮作系统。建议推广DR-W轮作作为稻麦轮作的主要生产方式。