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PEATWISE - Large effects of slightly different ground water tables on GHG emission from reed canary grass in paludiculture.

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Rewetting and abandoning drained peatland to restore the carbon sink function and to reduce greenhouse gas (GHG) emissions have often been recommended. Paludiculture, the combination of peatland rewetting and cultivation of flood-tolerant perennial crops for biorefining, biomaterials or bioenergy, has gained considerable interest as a possible alternative land use option. In 2011, field plots were established with reed canary grass in an agricultural fen peatland in Denmark. From spring 2015, the level of groundwater table (GWT) in
four plots was raised to -1 cm (annual mean) below soil surface by pumping water back from the drainage ditch leaving side-by-side plots with slightly lower ground water tables (-3 and -9 cm). Plots were fertilised with 80 kg N ha-1 in early spring and 80 kg N ha-1 after the first cut in mid-June. The final harvest was done on 1 October in both measurement years. Emissions of CH4 and N2O were measured with opaque chambers and net ecosystem exchange (NEE) of CO2 was measured with a temperature controlled transparent chamber using four levels of shrouding at biweekly intervals between March 2015 and February 2017.

Harvested biomass yield was on average 13.1 Mg DM ha-1 yr-1 across years and treatments without significant effect of GWT. NEE of CO2, ranging from -18.3 to -14.1 Mg CO2 ha-1 yr-1 (CO2 uptake), were similar for all three GWT treatments. In contrast, significant differences in CH4 emissions were measured with 27.8, 14.5 and 1.8 Mg CO2-eq ha-1 yr-1 at annual mean GWT of
-1, -3 and -9 cm, respectively. Emission of N2O ranged from 1.0 to 2.0 Mg CO2-eq ha-1 yr-1. Thus, the GWT of -9 cm was the most efficient regarding GHG mitigation, however, still being a source with emissions of 10.8 Mg CO2-eq ha-1 yr-1 including carbon removal with biomass (GWP N2O=265, CH4=28), respectively.
Udgivelsesår3 maj 2021
StatusUdgivet - 3 maj 2021
BegivenhedIPC 2021: International Peatland Congress - Online, Tallinn, Estland
Varighed: 3 maj 20216 maj 2021


KonferenceIPC 2021: International Peatland Congress

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