In this study, CO₂ exchange over sugarcane and wheat growing season was quantified by continuous measurement of CO₂ fluxes using eddy covariance (EC) system from January 2014 to June 2015. We also elaborated on the response of CO₂ fluxes to environmental variables. The results show that the ecosystem has seasonal and diurnal dynamics of CO₂ with a distinctive U-shaped curve in both growing seasons with maximal CO₂ absorption reaching up to −8.94 g C m⁻² day⁻¹ and −6.08 g C m⁻² day⁻¹ over sugarcane and wheat crop, respectively. The ecosystem as a whole acted as a carbon sink during the active growing season while it exhibits a carbon source prior to sowing and post-harvesting of crops. The cumulative net ecosystem exchange (NEE), gross primary productivity (GPP), and ecosystem respiration (R_eco) were −923.04, 3316.65, and 2433.18 g C m⁻² over the sugarcane growing season while the values were −192.30, 621.47, and 488.34 g C m⁻² over the wheat growing season. The sesbania (green manure) appeared to be a carbon source once it is incorporated into soil. The response of day-time NEE to photosynthetically active radiation (PAR) under two vapor pressure deficit (VPD) sections (0–20 h Pa and 20–40 h Pa) seems more effective over sugarcane (R² = 0.41–0.61) as compared to the wheat crop (R² = 0.25–0.40). A decrease in net CO₂ uptake was observed under higher VPD conditions. Similarly, night-time NEE was exponentially related to temperature at different soil moisture conditions and showed higher response to optimum soil moisture conditions for sugarcane (R² = 0.87, 0.33 ≤ SWC < 0.42 m³ m⁻³) and wheat (R² = 0.75, 0.31 ≤ SWC < 0.37 m³ m⁻³) crop seasons. The response of daily averaged NEE to environmental variables through path analysis indicates that PAR was the dominant predictor with the direct path coefficient of −0.65 and −0.74 over sugarcane and wheat growing season, respectively. Satellite-based GPP products from Moderate Resolution Imaging Spectroradiometer (GPP_MOD) and Vegetation Photosynthetic model (GPP_VPM) were also compared with the GPP obtained from EC (GPP_EC) technique. The seasonal dynamics of GPP_EC and GPP_VPM agreed well with each other. This study covers the broad aspects ranging from micro-meteorology to remote sensing over C4-C3 cropping system

在这项研究中，通过使用涡度协方差（EC）系统从2014年1月至2015年6月连续测量CO ₂通量来量化甘蔗和小麦生长期的CO ₂交换。我们还阐述了CO ₂通量对环境变量的响应。结果表明，对生态系统有CO的季节和昼夜动力学₂与最大CO在两个生长季节鲜明的U形曲线₂吸收达到高达-8.94克C M ^-2天^-1和-6.08克C M ^{- 2}天^-1分别在甘蔗和小麦作物上种植。整个生态系统在活跃的生长季节起着碳汇的作用，而在作物播种和收获后它表现出碳源。甘蔗生长期的累积净生态系统交换量（NEE），初级总生产力（GPP）和生态系统呼吸（R _eco）为-923.04、333.65和2433.18 g C m ^-2，而值分别为-192.30、621.47，和488.34 g C m ^-2在小麦的生长季节。一旦将芝麻（绿肥）掺入土壤中，它似乎是一种碳源。在两个蒸汽压亏缺（VPD）部分（0–20 h Pa和20–40 h Pa）下，白天NEE对光合有效辐射（PAR）的响应似乎比甘蔗（R ² = 0.41–0.61）更有效。与小麦作物相比（R ² = 0.25–0.40）。在较高的VPD条件下，观察到净CO ₂吸收量下降。同样，夜间NEE与不同土壤水分条件下的温度呈指数关系，对甘蔗的最佳土壤水分条件表现出更高的响应（R ² = 0.87，0.33≤SWC <0.42 m ³ m ^-3）和小麦（R ² = 0.75，0.31≤SWC <0.37 m ³ m ^-3）的作物季节。通过路径分析，每日平均NEE对环境变量的响应表明，在甘蔗和小麦生长期，PAR是主要的预测因子，其直接路径系数分别为-0.65和-0.74。来自中等分辨率成像光谱仪（GPP _MOD）和植被光合作用模型（GPP _VPM）的基于卫星的GPP产品也与从EC（GPP _EC）技术获得的GPP进行了比较。GPP _EC和GPP _VPM的季节性动态彼此同意。这项研究涵盖了从微气象到C4-C3种植系统的遥感等广泛领域