我国水稻品种更新与稻作技术改进对碳排放的综合影响及趋势分析

水稻是我国重要的口粮作物,稻田是全球第二大温室气体甲烷（CH₄）的最大排放源之一,水稻丰产与甲烷减排对保障国家粮食安全和实现农业领域碳中和目标意义重大。不同水稻品种和稻作技术的产量与碳排放差异显著,因此,掌握品种更新与技术改进的特征及发展趋势,可以为高产低碳稻作技术创新提供科学依据。为此,本文系统分析了1960s—2010s,我国水稻品种和稻作技术的演变特征及其对稻田温室气体排放的综合影响。总体而言,我国近50年来在品种不断更新和稻作技术显著改进及农用化学品大量投入下,水稻单产提高了37.0%,尽管单位面积碳排放增加12.2%,但是单位产量碳排放下降了18.1%,是一个增产减排的协同发展历程。基于情景分析,在保障国家粮食安全的条件下,综合水稻品种、灌溉方式、化肥减量以及稻作系统调整,以2010s为基线,我国2030s稻田温室气体总排放将下降17.0%以上,其中稻作技术改进和化学品增效减量的减排潜力最大。本研究可以为我国水稻产业可持续发展及农业领域“碳达峰碳中和”行动提供重要参考。

Integrated Impacts and Trend Analysis of Rice Cultivar Renewal and Planting Technology Improvement on Carbon Emission in China

Rice is the most important staple crop in China, and paddy field is one of the largest sources of anthropogenic CH₄ emissions in the world. To produce more rice with less CH₄ emission can contribute a great to ensuring national food security and carbon neutral objectives in China. Since different cultivars and planting practices lead to great differences in rice yield and carbon emission, an insight into the characteristics and trends of cultivar renewal and technology improvement can provide significant references to future innovation of rice planting technology for higher yield with less CH₄ emission. Therefore, we compared the characteristics and trends of China’s rice cultivar renewal and planting improvement as well as their impacts on carbon emission from 1960s to 2010s. Over the decades of 1970s—2010s, summarily, rice yield increased by 37.0% while total carbon emission at area-scaled increased by 12.2%, resulting in a significant decrease in yield-scaled carbon emission by 18.1% due to cultivar renewal, planting technology improvement and chemical input increase. Based on a scenario of ensuring food security, China’s carbon emission of rice production will decrease by 17.0% in 2030s as compared to the baseline of 2010s if all of the cultivar renewal, irrigation regime, chemical fertilizer reduction and cropping system adjustment can be comprehensively optimized, with the greatest potentials existed in rice planting improvement and chemical application with less rate and high efficiency. The results can provide great references to ensuring sustainable rice production and the actions of carbon emission peaking and carbon neutral in China.