Modeling lateral carbon fluxes for agroecosystems in the Mid-Atlantic region: Control factors and importance for carbon budget

Xi Luo; Avay Risal; Junyu Qi; Sangchul Lee; Xuesong Zhang; Joseph G Alfieri; Gregory W McCarty

doi:10.1016/j.scitotenv.2023.169128

Modeling lateral carbon fluxes for agroecosystems in the Mid-Atlantic region: Control factors and importance for carbon budget

Sci Total Environ. 2024 Feb 20:912:169128. doi: 10.1016/j.scitotenv.2023.169128. Epub 2023 Dec 7.

Authors

Xi Luo¹, Avay Risal¹, Junyu Qi², Sangchul Lee³, Xuesong Zhang⁴, Joseph G Alfieri⁴, Gregory W McCarty⁴

Affiliations

¹ Earth System Science Interdisciplinary Center, University of Maryland, College Park, 5825 University Research Ct, College Park, MD 20740, USA.
² Earth System Science Interdisciplinary Center, University of Maryland, College Park, 5825 University Research Ct, College Park, MD 20740, USA. Electronic address: junyuqi@umd.edu.
³ School of Environmental Engineering, 34-2, Seoulsiripdae-ro, Dongdaemun-gu, Seoul 02543, Republic of Korea.
⁴ USDA-ARS Hydrology and Remote Sensing Laboratory, Beltsville, MD 20705-2350, USA.

PMID: 38070562
DOI: 10.1016/j.scitotenv.2023.169128

Abstract

Estimating lateral carbon fluxes in agroecosystems presents challenges due to intricate anthropogenic and biophysical interactions. We used a modeling technique to enhance our comprehension of the determinants influencing lateral carbon fluxes and their significance in agroecosystem carbon budgets. The SWAT-C model was refined by incorporating a dynamic dissolved inorganic carbon (DIC) module, enhancing our ability to accurately quantify total lateral carbon fluxes. This improved model was calibrated using observed data on riverine particulate organic carbon (POC) and dissolved organic carbon (DOC) fluxes, as well as net ecosystem exchange (NEE) data monitored by a flux tower situated in a representative agricultural watershed, the Tuckahoe Watershed (TW) of the Chesapeake Bay's coastal plain. We assessed the losses of POC, DOC, and DIC across five primary rotation types: C (continuous carbon), CS (corn-soybean), CSS (corn-soybean-soybean), CWS (corn-wheat-soybean), and CWSCS (corn-wheat-soybean-corn-soybean). Our study revealed notable variations in the average annual fluxes of POC (ranging between 152 and 198 kg ha^-1), DOC (74-85 kg ha^-1), and DIC (93-156 kg ha^-1) across the five rotation types. The primary influencing factor for annual POC fluxes was identified as sediment yield. While both annual DOC and DIC fluxes displayed a marked correlation with surface runoff across all crop rotation schemes, soil respiration also significantly influenced annual DIC fluxes. Total lateral carbon fluxes (POC + DOC+DIC) constituted roughly 11 % of both net ecosystem production (NEP) and NEE, yet they represented a striking 95 % of net biome production (NBP) in the TW's agroecosystem. Grain yield carbon accounted for 80 % of both NEP and NEE and was nearly seven times that of NBP. Our findings suggest that introducing soybeans into cornfields tends to reduce NEP, NEE, and also NBP. Conversely, integrating winter wheat into the corn-soybean rotation significantly boosted NEP, NEE, and NBP values, with NBP even surpassing the levels in continuous corn cultivation.

Keywords: Agroecosystem; Carbon budget; Dissolved inorganic carbon; Dissolved organic carbon; Particulate organic carbon.