Greenhouse Gas Emissions Under Different Drainage and Flooding Regimes of Cultivated Peatlands

• Published in: Journal of geophysical research. Biogeosciences Vol. 122; no. 11; pp. 3047 - 3062
• Main Authors: Hu, Jing, VanZomeren, Christine M., Inglett, Kanika S., Wright, Alan L., Clark, Mark W., Reddy, K. R.
• Format: Journal Article
• Language: English
• Published: Washington Blackwell Publishing Ltd 01-11-2017
• Subjects: Agricultural production; Carbon dioxide; Carbon dioxide emissions; Climate change; Cores; Cycles; Drainage; Emissions; Everglades agricultural area; Farm buildings; Flooding; Floods; Global warming; global warming potential; Greenhouse effect; Greenhouse gases; histosols; Hydrologic regime; Hydrology; Methane; Nitrous oxide; Oxidation; Peatlands; Soil; Soils; Sustainability
• ISSN: 2169-8953; 2169-8961
• DOI: 10.1002/2017JG004010

Globally, approximately 10–20% of peatlands have been drained for agricultural purposes. A strategy to protect peatlands and mitigate carbon dioxide (CO2) emissions, while continuing agricultural production, is the use of intermittent flooding and drainage. A potential drawback of this strategy could be increases in methane (CH4) and nitrous oxide (N2O) emissions. The objective of this study was to compare greenhouse gas (GHG) emissions from peatlands under various flooding–drainage cycles. A laboratory study was performed using intact soil cores subjected to different durations of flooding and drainage for 6 months. Average daily emissions of CO2 and N2O were significantly higher (P < 0.001) under drained (667 ± 37 mg CO2–C m−2 d−1 and 135 ± 19 μg N2O–N m−2 d−1) than flooded conditions (86 ± 6 mg CO2–C m−2 d−1 and 48 ± 2 μg N2O–N m−2 d−1). Methane emissions were not influenced by drained/flooded conditions, with an average rate of 116 ± 11 μg CH4–C m−2 d−1. Peaks of CH4 and N2O emissions were observed after flooding events and lasted less than 24 h. The peak emissions were approximately 8 and 19 times higher than the mean CH4 and N2O emissions, respectively. Carbon dioxide was the dominant component of GHGs, irrespective of hydrologic regime, accounting for more than 92% of overall global warming potential. Global warming potential was inversely proportional to the flooding period, indicating that prolonging the flooding period of peatlands would help mitigate soil oxidation and GHG emissions and enhance sustainability of these agricultural peatlands.
Key Points
Global warming potential of greenhouse gas emissions from drained peatlands contributed by CO2 (>92%) was substantially higher than N2O (2–6%) and CH4 (<2%)
Application of drainage–flooding cycles on drained peatlands could decrease cumulative CO2 emissions without risks of increasing cumulative CH4 and N2O
Increasing the flooding period could significantly decrease the overall global warming potential of greenhouse gas emissions from drained peatlands