Carbon, Water, and Energy Flux Dynamics in Different Cropping Systems in the Great Lakes Region

Abstract

This study examined carbon (C), water, and energy exchanges across different cropping systems in the Great Lakes region using eddy covariance (EC) fluxes from an agricultural flux tower site (CA‐TPA) in southern Ontario, Canada. The site was cultivated with corn in 2020 and 2021, sweet potato in 2022, and tobacco in 2023. The site was a strong C sink during the corn years, with annual net ecosystem productivity (NEP) values of 538 ± 4.9 and 301 ± 3.7 g C m ⁻²  yr ⁻¹ in 2020 and 2021, respectively. In contrast, it became a C source in 2022 under sweet potato, exhibiting an annual NEP of −86 ± 2.1 g C m ⁻²  yr ⁻¹ . Under tobacco in 2023, the site transitioned to a weak carbon sink, with an annual NEP of 29 ± 1.6 g C m ⁻²  yr ⁻¹ . Crop yield (CY) was 537 and 491 g C m ² for corn in 2020 and 2021, respectively, 118 g C m ² for sweet potato in 2022, and 124 g C m ² for tobacco in 2023. It resulted in an annual net ecosystem carbon balance (NECB) of 1, −190, −205, and −95 g C m ² yr ⁻¹ for 2020, 2021, 2022, and 2023, respectively, indicating an overall net C loss from all three cropping systems after accounting for harvested biomass. Annual evapotranspiration (ET) totals were 661, 727, 745, and 722 mm yr ⁻¹ for 2020–2023, accounting for approximately 58%, 72%, 78%, and 74% of annual precipitation. The study results provide insights to support climate‐smart crop management practices in the region.