Abstract:

Collaboration towards achieving high yields and carbon reduction in rice production is crucial for ensuring national food self-sufficiency and attaining the goals of carbon peak and carbon neutrality. To quantitatively analyze the carbon footprint (CF) and composition characteristics of rice production in South China, multiple site field experiments were conducted in four representative rice-producing areas in Guangdong Province. The life cycle assessment method was employed to examine variations in rice yield, fertilizer utilization rate, indirect CF (CF_indirect), and its composition under different planting techniques. The results revealed that CF_indirect per unit area of indica rice production ranged from 1 235.3-1 487.7 kg CO₂-eq/hm², while CF_indirect per unit yield varied between 0.12-0.31 kg CO₂-eq/kg yield. The cultivation technique significantly influenced yield, fertilizer utilization efficiency, irrigation frequency, and CF_indirect per unit yield in rice production. Compared with the farmers conventional cultivation techniques (FP), the low-carbon and high-yielding cultivation technique (LC) significantly reduced the N fertilizer input and increased the grain yields. No significant interaction was found between the factors of cultivation techniques and rice varieties. The CF_indirect per unit yield was found to be significantly and negatively correlated with the yield under the same cultivation techniques, suggesting that adopting high-yielding varieties effectively mitigated CF_indirect per unit yield under the same cultivation technique. Multi-site demonstration experiments showed that LC technique increased rice grain yield by 3.67%-21.62% and improved the partial productivity of N fertilizer by 21.68%-60.81%, compared with FP. The implementation of LC technique led to an average reduction of irrigation frequency by 4 times during each cropping season. The CF_indirect per unit area and CF_indirect per unit yield in LC was decreased by 6.11% and 16.19%, respectively, compared with FP. N fertilizer and diesel were the primary factors influencing CF_indirect in rice production. Carbon emissions from diesel accounted for 49.65%-52.88% of the total CF_indirect, while emissions from N fertilizer contributed to 30.62%-34.70%. On average, reducing N fertilizer by 1 kg led to a reduction of CF_indirect by 2.49 kg CO₂-eq/hm². The indirect carbon footprint per unit yield was significantly and negatively correlated with fertilizer N partial productivity, indicating that the CF_indirect per unit yield could be effectively reduced by increasing yield and fertilizer N efficiency. In conclusion, the adoption of high-yield rice varieties in conjunction with optimized cultivation techniques effectively enhanced grain yield and fertilizer N efficiency, while simultaneously reduced both the CF_indirect per unit area and CF_indirect per unit yield. This ultimately achieved a synergistic balance between high yielding and low carbon emissions in rice production at South China.

Key words: indica rice, carbon footprint, life cycle assessment, carbon emission mitigation, low-carbon and high-yielding cultivation technology, South China

摘要： 协同实现水稻高产和碳减排对维护国家粮食自给和实现碳达峰碳中和意义重大。为定量分析华南地区水稻生产碳足迹及构成特征，明确栽培技术对水稻产量及碳足迹的影响，本研究在广东省4个典型的水稻产区开展田间试验，利用生命周期评价法分析不同栽培技术模式的水稻产量、肥料利用率和间接碳足迹及其构成。结果表明，广东省籼稻生产单位面积碳足迹为1 235.3~1 487.7 kg CO₂-eq/hm²，单位产量碳足迹为0.12~0.31 kg CO₂-eq/kg；栽培技术对水稻产量、化肥利用效率、灌溉次数和单位产量碳足迹有显著影响。与常规栽培技术相比，低碳高产栽培技术显著减少氮肥用量，并提高了水稻产量，栽培技术和品种之间无显著交互作用。相同技术模式下，单位产量间接碳足迹与产量呈极显著负相关，表明在相同种植条件下选用高产水稻品种能有效降低单位产量碳足迹。示范区的多点试验表明，与常规栽培技术相比，低碳高产栽培技术水稻产量增加3.67%~21.62%，氮肥偏生产力提高21.68%~60.81%，每季平均减少灌溉次数4次，单位面积碳足迹和单位产量碳足迹均值分别减少6.11%和16.19%。柴油和氮肥是影响间接碳足迹的关键因子，两者碳排放分别占总间接排放量49.65%~52.88%和30.62%~34.70%。平均每减少1 kg 氮肥，碳足迹降低2.49 kg CO₂-eq/hm²。水稻单位产量间接碳足迹与氮肥偏生产力呈极显著负相关，表明提高单位产量和氮肥利用率能有效减少水稻单产间接碳足迹。综上表明，华南地区水稻生产可通过选用高产水稻品种，结合水肥优化栽培技术降低氮肥和灌溉水投入，提高水稻产量和氮肥利用率，减少单位面积碳足迹和单位产量碳足迹，实现高产与低碳排的协同。

关键词: 籼稻, 碳足迹, 生命周期法, 碳减排, 低碳高产栽培技术, 华南