TY - JOUR
T1 - Two contrasting years of continuous N2O and CO2 fluxes on a shallow-peated drained agricultural boreal peatland
AU - Gerin, Stephanie
AU - Vekuri, Henriikka
AU - Liimatainen, Maarit
AU - Tuovinen, Juha-Pekka
AU - Kekkonen, Jarkko
AU - Kulmala, Liisa
AU - Laurila, Tuomas
AU - Linkosalmi, Maiju
AU - Liski, Jari
AU - Joki-Tokola, Erkki
AU - Lohila, Annalea
PY - 2023/10/15
Y1 - 2023/10/15
N2 - Drained agricultural boreal peatlands comprise a large source of nitrous oxide (N2O) and carbon dioxide (CO2) but a small sink or source of methane (CH4). N2O fluxes have high spatial and temporal variability and are often measured with the chamber technique. Therefore, continuous measurements of N2O fluxes are needed to better understand how N2O emissions are triggered and to reduce the uncertainty of annual N2O budget estimations. Here we present a two-year-long time series of continuous measurements of CO2 and N2O fluxes of a shallow-peated drained agricultural boreal peatland cultivated for grass silage. The fluxes were measured with the area-averaging eddy covariance technique. Several N2O peak events were observed throughout all seasons. The peaks were associated with meteorological or management events, such as soil thawing or freezing, precipitation, fertilization and glyphosate application. The annual N2O budget was 4.74 PLUSMN;0.47 and 6.08 PLUSMN;0.49 kg N2O-N ha-1 y-1in 2020 and 2021, respectively. The annual CO2 budget, comprising the sum of net ecosystem exchange and biomass export, was 3.70 PLUSMN;0.22 and 5.54 PLUSMN;0.33 t CO2-C ha-1 y-1 in 2020 and 2021, respectively. The N2O budget during the first, warmer winter was 106 meteorologically more typical winter, due to the higher frequency of soil freezing-thawing cycles. The average annual N2O budget was 3650EF) while the CO2 budget was in accordance with the IPCC EF. CO2 emissions dominated the total CO2-eq emissions of our site but N2O also had a significant contribution of 12O emissions in the last quarter of 2021. However, the full rotation should be measured to confirm whether there is a need to re-evaluate the N2O IPCC EF for `grassland drained boreal' land-use class.
AB - Drained agricultural boreal peatlands comprise a large source of nitrous oxide (N2O) and carbon dioxide (CO2) but a small sink or source of methane (CH4). N2O fluxes have high spatial and temporal variability and are often measured with the chamber technique. Therefore, continuous measurements of N2O fluxes are needed to better understand how N2O emissions are triggered and to reduce the uncertainty of annual N2O budget estimations. Here we present a two-year-long time series of continuous measurements of CO2 and N2O fluxes of a shallow-peated drained agricultural boreal peatland cultivated for grass silage. The fluxes were measured with the area-averaging eddy covariance technique. Several N2O peak events were observed throughout all seasons. The peaks were associated with meteorological or management events, such as soil thawing or freezing, precipitation, fertilization and glyphosate application. The annual N2O budget was 4.74 PLUSMN;0.47 and 6.08 PLUSMN;0.49 kg N2O-N ha-1 y-1in 2020 and 2021, respectively. The annual CO2 budget, comprising the sum of net ecosystem exchange and biomass export, was 3.70 PLUSMN;0.22 and 5.54 PLUSMN;0.33 t CO2-C ha-1 y-1 in 2020 and 2021, respectively. The N2O budget during the first, warmer winter was 106 meteorologically more typical winter, due to the higher frequency of soil freezing-thawing cycles. The average annual N2O budget was 3650EF) while the CO2 budget was in accordance with the IPCC EF. CO2 emissions dominated the total CO2-eq emissions of our site but N2O also had a significant contribution of 12O emissions in the last quarter of 2021. However, the full rotation should be measured to confirm whether there is a need to re-evaluate the N2O IPCC EF for `grassland drained boreal' land-use class.
KW - 4112 Forestry
KW - 114 Physical sciences
KW - N2O
KW - Eddy covariance
KW - Freeze-thaw cycle
KW - Fertilization
KW - Glyphosate application
KW - Drained peatland
U2 - 10.1016/j.agrformet.2023.109630
DO - 10.1016/j.agrformet.2023.109630
M3 - Article
SN - 0168-1923
VL - 341
JO - Agricultural and Forest Meteorology
JF - Agricultural and Forest Meteorology
M1 - 109630
ER -