华北平原基于麦玉轮作的粮薯、粮豆轮作模式碳足迹评价

Carbon Footprint Evaluation of Cereal-bean,Cereal-potato Rotation Modes Based on Wheat-maize Cropping System in North China Plain

针对华北平原冬小麦-夏玉米1年2熟长期复种连作导致的低效益、高碳排问题,以及面临保障口粮安全的艰巨任务,基于冬小麦-夏玉米轮作模式,加入甘薯和大豆形成粮薯、粮豆2年轮作模式,以期构建适宜该区域的稳粮、高效、生态种植制度。试验于2019年10月-2021年10月在河北省农林科学院宁晋基地进行,以冬小麦-夏玉米→冬小麦-夏玉米(麦玉模式)为对照,设置冬小麦-夏玉米→冬闲-春甘薯(粮薯模式)和冬小麦-夏玉米→冬小麦-夏大豆(粮豆模式)2种轮作模式,同时进行年际内重复,即冬闲-春甘薯→冬小麦-夏玉米和冬小麦-夏大豆→冬小麦-夏玉米。分析各轮作模式周年当量产量、碳排放和碳足迹差异。结果表明:与麦玉模式相比,粮薯模式的周年当量产量平均增加了29.10%,而粮豆模式的周年当量产量平均降低了6.03%。粮薯和粮豆模式显著降低了由农资生产、运输等过程导致的间接排放,主要降低了由化学氮肥和灌溉耗电导致的碳排放,比对照模式分别降低了40.5%和14.9%。与对照模式相比,粮薯和粮豆模式由氮肥施用导致的N 2 O直接排放量分别降低50.0%和32.4%,氨挥发间接排放量分别降低50.0%和29.6%,氮淋洗间接排放分别降低50.0%和26.4%。麦玉模式、粮薯和粮豆模式的周年总碳排放分别为13361.4,7468.2,10315.0 kg/hm^(2)。粮薯和粮豆模式的周年总碳排放比对照模式分别降低了44.1%和22.8%。与对照模式相比,粮薯和粮豆模式的单位面积碳足迹分别降低了44.1%和22.8%,单位生物量碳足迹分别降低了29.7%和9.4%。综上,将甘薯和大豆加入基于麦玉模式的轮作系统中可降低系统周年碳足迹。因此,从农田系统减排角度,粮薯和粮豆轮作模式可作为华北地区部分替代传统麦玉轮作的理论推荐模式。

Aiming at the problem of low economic efficiency and high carbon emission caused by long-term double cropping system of winter wheat-summer maize in North China Plain and facing to the arduous task of ensuring food security,this study was based on the winter wheat-summer maize rotation mode,and added sweet potato and soybean into the rotation system to form the cereal-potato and cereal-soybean rotation modes.In order to build a stable,efficient and ecological planting system suitable for this region,the experiment was conducted in Ningjin plot of Hebei Academy of Agriculture and Forestry Sciences from 2019-10 to 2021-10.There were two cropping modes:winter wheat-summer maize→fallow-spring sweet potato(cereal-sweet potato mode)and winter wheat-summer maize→winter wheat-summer soybean(cereal-soybean mode).Inter-annual repetitions were carried out at the same time,namely,fallow-spring sweet potato→winter wheat-summer maize and winter wheat-summer soybean→winter wheat-summer maize.The differences of annual equivalent yield,net benefit,carbon emission and carbon footprint under different cropping rotations were analyzed.The results showed that:Compared with wheat-maize mode,the annual equivalent yield of cereal-sweet potato mode increased by 29.10%.Meanwhile,the annual equivalent yield of cereal-soybean mode decreased by 6.03%.Cereal-sweet potato and cereal-soybean modes significantly reduced the indirect emissions caused by agricultural materials production and transportation and mainly reduced carbon emissions from chemical nitrogen fertilizers and irrigation electricity.Compared with that of CK,the reduction was 40.5%and 14.9%,respectively.Compared with that of CK,cereal-sweet potato and cereal-soybean modes reduced N 2 O direct emissions caused by nitrogen fertilizer application by 50.0%and 32.4%,and indirect emissions caused by ammonia volatilization by 50.0%and 29.6%,respectively,and indirect emission caused by nitrogen leaching decreased by 50.0%and 26.4%,respectively.The annual total carbon emission of CK,cereal-sweet potato mode and cereal-soybean mode were 13361.4,7468.2,and 10315.0 kg/ha,respectively.The annual total carbon emissions of cereal-sweet potato and cereal-soybean modes decreased by 44.1%and 22.8%,respectively,compared with that of the control mode.Compared with that of CK,the carbon footprint per unit area of cereal-sweet potato and cereal-soybean modes decreased by 44.1%and 22.8%,the carbon footprint per unit biomass decreased by 29.7%and 9.4%,respectively.In all,adding sweet potato and soybean to wheat-maize cropping system could reduce carbon footprint.Therefore,from the perspective of emission reduction,cereal-sweet potato and cereal-soybean modes can be recommended as a theoretical model to partially replace the traditional wheat-maize mode in North China Plain.