Carbon, Water, and Energy Exchanges in a Sweet Potato Agricultural Field in the Great Lakes Region

Abstract

Carbon, water, and energy exchanges were measured in an agricultural field in the Great Lakes region near Turkey Point in southeastern Ontario, Canada. The site is part of Turkey Point Environmental Observatory and associated with the Ameriflux, global Fluxnet, Global Water Future Observatories and Global Centre for Transboundary Waters initiatives. It is known as CA-TPA in Ameriflux and global Fluxnet. In this study energy, water and carbon fluxes as well as meteorological and hydrological variables were measured in Sweet Potato (Ipomoea batatas) crop for two years (2022 and 2024). An open-path eddy covariance system and an automatic weather station were used for this purpose. The field was planted with a cover crop (rye grass and winter wheat) in both years during the winter months which was mowed into the soil in April. Sweet potato was planted in June and harvested in October with harvested crop yield of about 25 and 30 metric tons ha-1 in 2022 and 2024, respectively. The study results showed that on an annual basis the field was a net source of carbon in 2022 and a small sink of carbon in 2024 with net ecosystem productivity (NEP) of -86 ± 10 and 34 ± 11 g C m-2 y-1, respectively. Corresponding annual net ecosystem carbon balance (NECB) values were -630 and -619 g C m⁻² y⁻¹, in 2022 and 2024, respectively. Respective annual evapotranspiration (ET) values were 746 and 759 mm y-1. This sweet potato focused study is aimed to fill a current gap in the literature, as it is a crop that is rarely observed for its carbon sequestration potential as well as energy and water dynamics in North America. It also underscores the necessity of considering diverse crop types when exploring their potential for carbon sequestration and nature-based solutions to climate change.