Investigating CO₂ fluxes and carbon budget in agro-ecosystems is essential to develop climate smart agriculture. Here, we conducted a thorough analysis on the daily, seasonal and inter-annual variations in CO₂ fluxes and carbon budget in a winter-wheat and summer-maize rotation system in the North China Plain (NCP) to better understand the CO₂ flux exchange and the underlying mechanisms of carbon budget dynamics. During 2003-2010, the inter-annual variability of monthly gross primary productivity was significantly correlated with leaf area index (LAI), temperature and net radiation. The inter-annual variability of monthly ecosystem respiration was significantly correlated with LAI, soil temperature and moisture. Daily and monthly variability in net ecosystem exchange (NEE) was significantly correlated with LAI. At a seasonal scale, soil moisture was one of the primary factors controlling carbon sequestration of wheat system. Nitrogen application rate and water conditions were the primary factors controlling carbon sequestration of maize system. The NEE for winter wheat system, maize system, and winter wheat-maize rotation system in the NCP ranged from -418 to -29, -448 to -119, and -857 to -274 gCm⁻², respectively. The net biome productivity (NBP) for winter wheat system, maize system, and winter wheat-maize rotation system in the NCP ranged from -223 to 151, -236 to 94, and -239 to 237 gCm⁻², respectively. Taking greenhouse gas (GHG) emissions from irrigation, fertilization, herbicides, fungicide, insecticide, and field operations, the associated net GHG emissions ranged from -39 to 325 gCm⁻² for wheat system and -22 to 287 gCm⁻² for maize system. Wheat and maize systems in the region were a medium source of GHG emissions in most of years, mainly due to the large application rates of fertilization and irrigation. Our findings gain new insights into the mechanisms underlying the inter-annual variations in CO₂ fluxes and carbon budget, highlighting the optimization of genotype, environment and management interactions to realize climate smart agriculture.

调查农业生态系统中的 CO ₂通量和碳收支对于发展气候智能型农业至关重要。在这里，我们对华北平原（NCP）冬小麦夏玉米轮作系统中CO ₂通量和碳收支的日、季节和年际变化进行了深入分析，以更好地了解CO ₂通量交换和碳收支动态的潜在机制。2003-2010年间，月总初级生产力的年际变化与叶面积指数（LAI）、温度和净辐射显着相关。月生态系统呼吸的年际变化与LAI、土壤温度和水分显着相关。净生态系统交换 (NEE) 的每日和每月变化与 LAI 显着相关。在季节尺度上，土壤水分是控制小麦系统固碳的主要因素之一。施氮量和水分条件是控制玉米系统固碳的主要因素。华北地区冬小麦系统、玉米系统和冬小麦-玉米轮作系统的 NEE 范围为 -418 至 -29、-448 至 -119，^-2，分别。NCP中冬小麦系统、玉米系统和冬小麦-玉米轮作系统的净生物群落生产力（NBP）分别为-223至151、-236至94和-239至237 gCm ^-2。考虑灌溉、施肥、除草剂、杀菌剂、杀虫剂和田间作业产生的温室气体 (GHG) 排放量，小麦系统的相关温室气体净排放量范围为 -39 至 325 gCm ^-2和玉米系统的-22 至 287 gCm ^-2 . 在大多数年份，该地区的小麦和玉米系统是温室气体排放的中等来源，这主要是由于施肥和灌溉的大量施用。_{我们的研究结果对 CO 2}年际变化的机制有了新的认识通量和碳预算，突出优化基因型、环境和管理相互作用以实现气候智能型农业。