The middle and lower reaches of the Yangtze River is one of main grain production areas in China, which is of great significance to food security. Understanding the carbon footprint of major grain crop production is helpful to develop high-yield and low-carbon agriculture. Based on the data of yield, sown area and farmland production input of main grain crops (rice, wheat and maize) in six provinces (Jiangsu, Anhui, Jiangxi, Hubei, Hunan, and Zhejiang) in the middle and lower reaches of the Yangtze River from 2011 to 2020, we estimated carbon footprint in the production of the three grain crops. The results showed that from 2011 to 2020, yield per unit area, planting area, and total yield of rice, wheat and maize were the highest in Jiangsu Province. In terms of area-scaled carbon footprint, rice in the middle and lower reaches of the Yangtze River had the highest area-scaled carbon footprint, with an average of 2.0 t CE·hm-2, followed by wheat and maize. The area-scaled carbon footprint of the three staple crops was increasing. In terms of yield-scaled carbon footprint, rice was the highest, with an average of 0.8 kg CE·kg-1, followed by wheat and maize. In terms of carbon input structure, irrigation electricity, chemical fertilizers and pesticides accounted for a relatively high proportion. Irrigation electricity accounted for 35.0%, 36.3%, and 33.2% of the total carbon input of rice, wheat and maize, respectively. Chemical fertilizers accounted for 28.8%, 32.5%, and 32.5%, respectively, while pesticides accounted for 24.2%, 13.3% and 11.5%, respectively. In terms of carbon efficiency, maize had the highest (3.9 kg·kg-1 CE), followed by rice and wheat. With the green development of agriculture, carbon emission in the production of major grain crops in the middle and lower reaches of the Yangtze River could be reduced by improving irrigation efficiency, fertilizer utilization efficiency, pesticide utilization efficiency and mechanized operation efficiency, as well as diversification of straw returning, cultivation of new varieties and policy leverage.
长江中下游是我国粮食生产区之一,对粮食安全保障有重要意义。解析主要粮食作物生产的碳足迹,有助于发展丰产低碳农业。本研究基于2011—2020年长江中下游地区6个省份(江苏省、安徽省、江西省、湖北省、湖南省和浙江省)主要粮食作物(水稻、小麦和玉米)的产量、播种面积、农田生产投入等数据,对该区域上述3种主粮作物的生产碳足迹进行估算。结果表明: 2011—2020年间,江苏省的水稻、小麦和玉米不论在单产、种植面积或总产上均居首位。在单位面积碳足迹上,长江中下游地区的水稻最高,平均达到2.0 t CE·hm-2,小麦次之,玉米最低,且3种主粮作物的单位面积碳足迹不断升高。在单位籽粒产量碳足迹上,水稻最高,平均达到0.8 kg CE·kg-1,小麦次之,玉米最低。在碳投入结构上,灌溉用电、化肥和农药的投入占比较高,灌溉用电分别占水稻、小麦和玉米总碳投入的35.0%、36.3%和33.2%,化肥分别占28.8%、32.5%和32.5%,农药分别占24.2%、13.3%和11.5%。在碳效率上,玉米最高,为3.9 kg·kg-1 CE,水稻次之,小麦最低。随着农业绿色发展的推进,通过提高灌溉效率、化肥利用效率、农药利用率和机械化作业效率,以及秸秆还田多样化、新品种培育和政策杠杆等多种途径,能够合力降低长江中下游地区主要粮食作物生产过程中的碳排放。.