Substantial carbon loss respired from a corn-soybean agroecosystem highlights the importance of careful management as we adapt to changing climate

Authors: MOORE, CAITLIN - University Of Illinois; GIBSON, CHRISTY - University Of Illinois; MIAO, GUOFANG - Fujian Normal University; DRACUP, EVAN - University Of Illinois; GOMEZ-CASANOVAS, NURIA - University Of Illinois; MASTERS, MICHAEL - University Of Illinois; MILLER, JESSE - Environmental Protection Agency (EPA); VON HADEN, ADAM - University Of Illinois; MEYERS, TILDEN - National Oceanic & Atmospheric Administration (NOAA); DELUCIA, EVAN - University Of Illinois; Bernacchi, Carl

Submitted to: Environmental Research Letters
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/11/2022
Publication Date: 4/28/2022
Citation: Moore, C.E., Gibson, C.D., Miao, G., Dracup, E.C., Gomez-Casanovas, N., Masters, M.D., Miller, J., von Haden, A., Meyers, T., DeLucia, E., Bernacchi, C.J. 2022. Substantial carbon loss respired from a corn-soybean agroecosystem highlights the importance of careful management as we adapt to changing climate. Environmental Research Letters. 17(5). Article 054029. https://doi.org/10.1088/1748-9326/ac661a.
DOI: https://doi.org/10.1088/1748-9326/ac661a

Interpretive Summary: Agricultural crop fields drive the uptake and release of carbon dioxide from and to the atmosphere. Because of this, it is important to understanding how variation in climate and weather impact the exchange of carbon dioxide. In this study, a ten year experiment was conducted on a corn and soybean rotation field with the goal of addressing how carbon dioxide moves into or out of the ecosystem. A significant fraction of carbon dioxide is shown to leave the ecosystem primarily during the growing season in two years following a drought. The results from this analysis suggest that despite high photosynthetic rates, ecosystem function is altered in years following a drought that corresponds with a large release of carbon dioxide. This carbon dioxide 'burp' that was measured suggests that there is potential for more carbon release from soils when droughts become more prevalent with global warming.

Technical Abstract: Understanding agroecosystem carbon (C) cycle response to climate change and management is vital for maintaining their long-term C storage. We demonstrate this importance through an in-depth examination of a 10-year eddy covariance dataset from a corn-corn-soybean crop rotation grown in the Midwest United States. 10-year average annual net ecosystem exchange (NEE) showed a net C sink of -0.39 Mg C ha-1 y-1. However, NEE in 2014 and 2015 from the corn ecosystem was 3.58 and 2.56 Mg C ha-1 y-1, respectively. Most C loss occurred during the growing season, when photosynthesis should dominate and C fluxes should reflect a net ecosystem gain. Partitioning NEE into gross primary productivity (GPP) and ecosystem respiration (ER) showed this C “burp” was driven by higher ER, with a 51% (2014) and 57% (2015) increase from the 10-yea average (15.84 Mg C ha-1 y-1). GPP was also higher than average (16.24 Mg C ha-1 y-1) by 25% (2014) and 37% (2015), but this was not enough to offset the C emitted from ER. This increased ER was likely driven by enhanced soil microbial respiration associated with ideal growing season climate, substrate availability, nutrient additions, and a potential legacy effect from drought.