The arid and semi-arid regions of northwest China play a crucial role in ensuring the national cotton production. Soil water potential (SWP)-based deficit irrigation is potentially an effective irrigation strategy in maintaining agricultural productivity in these regions. However, the impact of various SWP thresholds and nitrogen application rates on carbon balance and environmentally friendly economic benefits in cotton systems remains unclear. A two-year field experiment was conducted to investigate the effects of three SWP thresholds (W1, W2 and W3: −30, −20 and −10 kPa) and three nitrogen rates (F1, F2 and F3: 200, 300 and 400 kg ha) on greenhouse gas (GHG) emissions, seed cotton yield, carbon storage, and economic benefits in drip-fertigated saline cotton fields. The results showed that increasing nitrogen rate significantly increased NO emission, while higher irrigation level reduced the soil's capacity to absorb CH. Moreover, increasing irrigation level and nitrogen rate led to higher soil CO emission. The W3F3 obtained the highest seed cotton yield, ranging from 6529.6 to 6804.6 kg ha. Nitrogen application increased soil organic carbon storage by 5.6–12.5 %, whereas excessive nitrogen fertilization resulted in significant losses in soil inorganic carbon, ranging from 20.7 % to 34.9 %. The W2F2 enhanced net ecosystem carbon budget accumulation by increasing the input efficiency of carbon and reducing GHG emissions, and excessive GHG emissions limited the net ecosystem carbon budget of high-fertilization treatments. Meanwhile, the increased fertilizer and environmental costs reduced net ecosystem economic benefit. Fertilizer was identified as the major contributor to the ecosystem carbon footprint, accounting for more than 22.9 %. In conclusion, the W2F2 not only obtained the optimal soil carbon sequestration and carbon balance in the system, but also generated economic profits comparable to those of the high-fertilization treatments while producing lower direct GHG emissions. These findings highlight the significance of rational drip irrigation and nitrogen fertilization in maintaining high productivity and carbon sustainability in saline cotton fields.

中文翻译：

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优化滴灌和氮肥施肥制度，减少温室气体排放，增加净生态系统碳预算，减少盐渍棉田的碳足迹

西北干旱半干旱地区对保障全国棉花生产发挥着至关重要的作用。基于土壤水势（SWP）的赤字灌溉可能是维持这些地区农业生产力的有效灌溉策略。然而，各种SWP阈值和施氮量对棉花系统碳平衡和环境友好型经济效益的影响仍不清楚。进行了为期两年的田间试验，研究了三个 SWP 阈值（W1、W2 和 W3：-30、-20 和 -10 kPa）和三个施氮量（F1、F2 和 F3：200、300 和 400 kg）的影响公顷）关于滴灌施肥盐棉田的温室气体（GHG）排放、籽棉产量、碳储存和经济效益。结果表明，增加施氮量显着增加了NO的排放，而较高的灌溉水平降低了土壤吸收CH的能力。此外，灌溉水平和施氮量的增加导致土壤二氧化碳排放量增加。W3F3获得了最高的籽棉产量，范围为6529.6至6804.6公斤公顷。施氮使土壤有机碳储量增加5.6%~12.5%，而过量施氮导致土壤无机碳显着损失，损失幅度为20.7%~34.9%。W2F2通过提高碳的输入效率和减少温室气体排放来增强净生态系统碳预算积累，过量的温室气体排放限制了高施肥处理的净生态系统碳预算。同时，肥料和环境成本的增加降低了生态系统的净经济效益。肥料被确定为生态系统碳足迹的主要贡献者，占22.9%以上。综上所述，W2F2不仅获得了系统内最优的土壤固碳和碳平衡，而且在产生较低的直接温室气体排放的同时，也产生了与高施肥处理相当的经济效益。这些发现凸显了合理滴灌和施氮肥对于维持盐渍棉田高生产力和碳可持续性的重要性。