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ARS Home » Southeast Area » Jonesboro, Arkansas » Delta Water Management Research » Research » Publications at this Location » Publication #359438
Research Project: Preserving Water Availability and Quality for Agriculture in the Lower Mississippi River Basin

Location: Delta Water Management Research

Title: Fallow season CO2 and CH4 fluxes from U.S. mid-south rice-waterfowl habitats

Author
item Reba, Michele
item FONG, BRYANT - Orise Fellow
item RIJAL, ISHARA - Arkansas State University

Submitted to: Agricultural and Forest Meteorology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/14/2019
Publication Date: 6/1/2020
Citation: Reba, M.L., Fong, B.N., Rijal, I. 2020. Fallow season CO2 and CH4 fluxes from U.S. mid-south rice-waterfowl habitats. Agricultural and Forest Meteorology. 75(3):291-303. https://doi.org/10.2489/jswc.75.3.291.
DOI: https://doi.org/10.2489/jswc.75.3.291

Interpretive Summary: Flooding rice fields in the U.S. mid-south during the fallow season (November-March) for migratory bird habitats provides revenue from hunting-related activities and helps with soil retention and water quality. However, flooding has the potential to increase greenhouse gas (GHG) emissions. Research on GHG emissions during this time has been limited. Field integrated measurements of carbon dioxide (CO2) and methane (CH4) fluxes were collected during the fallow seasons of 2015, 2016 and 2017 at paired fields in NE Arkansas. The paired fields consisted of one field flooded (F) with precipitation by installing barriers to prevent drainage and the other field allowed to drain or was non-flooded (NF). Emissions from the fallow season accounted for 32-34% of the growing season CO2 emissions and 20-22% of growing season CH4 emissions, with fallow flooding contributing roughly 2% more than NF fields. Flooding did not influence CO2 emissions significantly. However, considering only the fallow season, F fields emitted 45±2% more CH4 than NF fields. These findings will improve our overall understanding and modeling of GHG emissions from agricultural fields during an understudied but important period of the year.

Technical Abstract: Flooding rice fields in the U.S. mid-south during the fallow season (November-March) for migratory bird habitats provides revenue from hunting-related activities and helps with soil retention and water quality. However, flooding has the potential to increase greenhouse gas (GHG) emissions. Research on GHG emissions during this time has been limited. Eddy covariance (EC) systems measuring CO2 and CH4 fluxes were installed during the 2015-2016, 2016-2017, and 2017-2018 fallow seasons and during the previous growing seasons at paired fields in NE Arkansas. The paired fields consisted of one field flooded (F) with precipitation by installing barriers to prevent drainage and the other field allowed to drain or non-flooded (NF). Emissions from the fallow season accounted for 32-34% of the growing season CO2 emissions and 20-22% of growing season CH4 emissions, with fallow flooding contributing roughly 2% more than NF fields. Flooding did not influence CO2 emissions significantly. However, considering only the fallow season, F fields emitted 45±2% more CH4 than NF fields. The three-year fallow season average was 1355±132 kg CO2-C ha-1 season-1 and 8.6±1.4 kg CH4-C ha-1 season-1 in NF fields, and 1408±185 kg CO2-C ha-1 season-1 and 12.5±2.0 kg CH4-C ha-1 season-1 in F fields. Methane contributed on average 7±1% to total fallow season global warming potential (GWP), reported as CO2 equivalents from CO2 and CH4 measurements. The three-year fallow season average GWP was 5256±488 kg-CO2-eq season-1 from NF fields and 5581±678 kg-CO2-eq season-1 from F fields. These findings will improve our overall understanding and modeling of GHG emissions from agricultural fields during an understudied but important period of the year.