华北平原小麦-玉米轮作系统碳中和潜力及固碳措施

Carbon neutralization potential and carbon sequestration efforts in a wheatmaize rotation system in the North China Plain

农业碳中和是将工业生产的二氧化碳(CO_(2))用于农业生产的有效手段。针对国家提出的CO_(2)排放于2030年前达到峰值(碳达峰), 2060年前实现碳中和目标,我们利用“静态箱-涡度相关-生物量监测法”明确了华北平原农业非能源碳平衡;同时结合农户抽样调查和农事活动碳排放系数明确了农业能源碳排放,进而计算出该区域农田的碳中和潜力。结果表明:小麦-玉米轮作农田净截存的有机碳量小麦季和玉米季分别为604 g(C)·m^(-2)和540 g(C)·m^(-2)。考虑农田生态系统的呼吸损耗,该区域小麦季和玉米季非能源碳净碳固存量分别为-359 g(C)·m^(-2)和-143 g(C)·m^(-2)。通过对农地投入中能源碳排放的研究发现,冬小麦季农药、化肥、农用机械消耗柴油及农地灌溉的碳排放分别为3.74 g(C)·m^(-2)、90.70 g(C)·m^(-2)、5.68 g(C)·m^(-2)和2.05 g(C)·m^(-2),玉米季分别为2.89 g(C)·m^(-2)、53.70 g(C)·m^(-2)、10.20 g(C)·m^(-2)和2.05 g(C)·m^(-2)。综合非能源(包括籽粒固碳)和能源碳观测,华北平原冬小麦季和夏玉米季均为碳汇,其强度分别为-257 g(C)·m^(-2)和-74 g(C)·m^(-2)。以华北平原典型集约高产粮区——河北栾城为例,其每年冬小麦和夏玉米农田的碳中和潜力分别为3.8×10^(10)g(C)和9.4×10^(9)g(C)。此外加强耕地管理,推广农业低碳化和发展富碳农业均可作为该区域有效的固碳措施。总之,本研究明确了华北平原小麦-玉米轮作农田的碳汇强度,估算了该农田系统在河北栾城的碳中和潜力,并提出了有效的固碳措施。

Agricultural C neutralization is an effective method of using industrial carbon dioxide(CO_(2)) in agricultural production.Aiming at the national goal of “peaking CO_(2)emissions before 2030 and achieving carbon neutrality before 2060”, we defined the agricultural non-energy C balance in the North China Plain(NCP) by using the “static chamber-eddy covariance-biomass monitoring method”. Simultaneously, C emissions from agricultural energy were determined based on the sampling survey data of farmers and the C emission coefficients of agricultural activities. Thus, the C neutralization potential of croplands in this region was calculated.Our results showed that in the NCP, the net amount of organic C(including grains and returned straw) for winter wheat and summer maize was 604 g(C)·m^(-2)and 540 g(C)·m^(-2), respectively. Considering the ecosystem autotrophic respiration consumption, the net C sequestration of non-energy C was-359 g(C)·m^(-2)and-143 g(C)·m^(-2)in the wheat and maize seasons, respectively. Energy C emissions in the system were further studied. The C emissions of pesticides, chemical fertilizers, agricultural diesel, and irrigation in the wheat season were 3.74, 90.70, 5.68, and 2.05 g(C)·m^(-2), respectively;and those in the maize season were 2.89, 53.70, 10.20, and 2.05g(C)·m^(-2), respectively. Combined with the non-energy and energy C budget, both the winter wheat and summer maize seasons were C sinks,-257 g(C)·m^(-2)for the winter wheat season and-74 g(C)·m^(-2)for the summer-maize season. For example, in Luancheng(located in Hebei Province), a typical intensive and high-yield grain region in the NCP, the annual C sequestration potential of winter wheat and summer maize croplands was 3.8×10^(10)g C and 9.4×10^(9)g C, respectively. In addition, strengthening cultivated land management, promoting low-C agriculture, and developing C-rich agriculture can be effective strategies for C sequestration in this region.In conclusion, we identified the C sink intensity of winter wheat and summer maize rotation cropland in the NCP, estimated the C neutralization potential in Luancheng, Hebei Province, and proposed effective C sequestration efforts.