TY - JOUR

T1 - Greenhouse Gas Balance of Sphagnum Farming on Highly Decomposed Peat at Former Peat Extraction Sites

AU - Oestmann, Jan

AU - Tiemeyer, Bärbel

AU - Düvel, Dominik

AU - Grobe, Amanda

AU - Dettmann, Ullrich

N1 - Funding Information: This research was funded by the Lower Saxony Ministry for Nutrition, Agriculture and Consumer Protection (ML, AZ 105.1-3234/1-13-3) and the German Federal Environmental Foundation (DBU, AZ 33305/01-33/0). The permissions granted by the Weser-Ems Office for Regional State Development (State Bog Administration) and the County Emsland have facilitated the project. We thank our project partners at Klasmann-Deilmann GmbH for the productive cooperation. We gratefully thank two anonymous reviewers for their knowledgeable and constructive comments. We also want to express our thanks to Kerstin Gilke and Andrea Oehns-Rittgerodt for gas chromatograph analyses; Sabine Wathsack, Ute Tambor, Thomas Viohl and Claudia Wiese for water, soil and biomass analysis, Frank Hegewald and Dirk Lempio for technical assistance in the field, and Arndt Piayda for data on hydraulic conductivity and soil sampling together with Mareille Wittnebel. Finally, we would also like to thank the students who helped in the field and in the laboratory.

PY - 2022/3

Y1 - 2022/3

N2 - For two years, we quantified the exchange of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) at two different large-scale Sphagnum farming sites. At both, peat extraction left a shallow layer of highly decomposed peat and low hydraulic conductivities. One site was characterized by preceding multi-annual inundation and irrigated by ditches, while the other one was inoculated directly after peat extraction and irrigated by ditches and drip irrigation. Further, GHG emissions from an irrigation polder and the effect of harvesting Sphagnum donor material at a near-natural reference site were determined. GHG mitigation potentials lag behind the results of less decomposed sites, although our results were also affected by the extraordinary hot and dry summer 2018. CO2 exchanges ranged between -0.6 and 2.2 t CO2-C ha−1 y−1 and were mainly influenced by low water table depths. CH4 emissions were low with the exception of plots with higher Eriophorum covers, while fluctuating water tables and poorly developing plant covers led to considerable N2O emissions at the ditch irrigation site. The removal of the upper vegetation at the near-natural site resulted in increased CH4 emissions and, on average, lowered CO2 emissions. Overall, best plant growth and lowest GHG emissions were measured at the previously inundated site. At the other site, drip irrigation provided more favourable conditions than ditch irrigation. The size of the area needed for water management (ditches, polders) strongly affected the areal GHG balances. We conclude that Sphagnum farming on highly decomposed peat is possible but requires elaborate water management.

AB - For two years, we quantified the exchange of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) at two different large-scale Sphagnum farming sites. At both, peat extraction left a shallow layer of highly decomposed peat and low hydraulic conductivities. One site was characterized by preceding multi-annual inundation and irrigated by ditches, while the other one was inoculated directly after peat extraction and irrigated by ditches and drip irrigation. Further, GHG emissions from an irrigation polder and the effect of harvesting Sphagnum donor material at a near-natural reference site were determined. GHG mitigation potentials lag behind the results of less decomposed sites, although our results were also affected by the extraordinary hot and dry summer 2018. CO2 exchanges ranged between -0.6 and 2.2 t CO2-C ha−1 y−1 and were mainly influenced by low water table depths. CH4 emissions were low with the exception of plots with higher Eriophorum covers, while fluctuating water tables and poorly developing plant covers led to considerable N2O emissions at the ditch irrigation site. The removal of the upper vegetation at the near-natural site resulted in increased CH4 emissions and, on average, lowered CO2 emissions. Overall, best plant growth and lowest GHG emissions were measured at the previously inundated site. At the other site, drip irrigation provided more favourable conditions than ditch irrigation. The size of the area needed for water management (ditches, polders) strongly affected the areal GHG balances. We conclude that Sphagnum farming on highly decomposed peat is possible but requires elaborate water management.

UR - http://www.scopus.com/inward/record.url?scp=85110937570&partnerID=8YFLogxK

U2 - 10.1007/s10021-021-00659-z

DO - 10.1007/s10021-021-00659-z

M3 - Article

AN - SCOPUS:85110937570

VL - 25

SP - 350

EP - 371

JO - ECOSYSTEMS

JF - ECOSYSTEMS

SN - 1432-9840

IS - 2

ER -