TY - JOUR

T1 - High greenhouse gas emissions after grassland renewal on bog peat soil

AU - Offermanns, Liv

AU - Tiemeyer, Bärbel

AU - Dettmann, Ullrich

AU - Rüffer, Jeremy

AU - Düvel, Dominik

AU - Vogel, Isabelle

AU - Brümmer, Christian

N1 - Funding Information: The project "Gnarrenburger Moor" (application no. ZW 6–85023359) is funded by the European Regional Development Fund, the Lower Saxony Ministry of Food, Agriculture and Consumer Protection and the Lower Saxony Ministry of the Environment, Energy and Climate Protection. Chris Evans and an anonymous reviewer greatly helped to improve the manuscript by insightful comments and suggestions. We thank the project team of the Project “Gnarrenburger Moor” at the State Authority for Mining, Energy and Geology Lower Saxony and at the Chamber of Agriculture. Special thanks also to the cooperating farmers. We also want to express our thanks to Arne Heidkamp and Daniel Ziehe with their laboratory teams, especially Kerstin Gilke and Andrea Oehns-Rittgerodt for gas chromatograph analyses. Andrea Niemeyer, Manuela Rutsch, Adina Schlegel, Nicole Altwein, Ute Tambor, Sabine Wathsack, Dagmar Wenderoth, and Claudia Wiese for water, soil, and biomass analyses. Thanks also to the State Authority for Mining, Energy and Geology Lower Saxony for provision of water level and surface elevation data. We further thank Jean-Pierre Delorme, Jens-Kristian Jüdt, Frank Hegewald, Dirk Lempio, and Thomas Viohl for technical assistance in the field. We also want to thank all members of the working groups of Bärbel Tiemeyer and Christian Brümmer at the Thünen Institute of Climate-Smart Agriculture for all kinds of help in the field, as well as for technical and scientific support. Finally, we would like to thank all the students who helped in the field and in the laboratory, especially Marit Baumeister and Timothy Husting. Funding Information: The project "Gnarrenburger Moor" (application no. ZW 6–85023359 ) is funded by the European Regional Development Fund , the Lower Saxony Ministry of Food, Agriculture and Consumer Protection and the Lower Saxony Ministry of the Environment, Energy and Climate Protection .

PY - 2023/3/15

Y1 - 2023/3/15

N2 - Drained agriculturally used peatlands are hotspots for greenhouse gas (GHG) emissions, especially carbon dioxide (CO2) and nitrous oxide (N2O). To reduce GHG emissions and simultaneously maintain intensive grassland use, raising water levels by subsurface irrigation (SI) is controversially discussed. Both, intensive grassland use and installations of SI may require grassland renewal. We investigated an experimental intervention site (INT) (SI target water levels: -0.30 m) and a deeply drained reference site (REF), both intensive grassland on deep bog peat. After installation of the SI system, a mechanical grassland renewal took place at INT. At both sites, CO2 (eddy covariance), N2O and methane (manual closed chamber technique) were measured. Additionally, soil water was analyzed for nitrogen species. Here, we report on the initial year of GHG measurements including grassland renewal and rising water levels. Overall, GHG emissions were strongly influenced by grassland renewal at INT. Despite progressively rising water levels, soil moisture in the upper centimeters was low and thus grass growth was slow, resulting in an almost complete loss of harvest. This resulted in a net ecosystem carbon balance (NECB) of 4.64 ± 1.03 t C ha−1 containing only 0.57 ± 0.09 t C ha−1 harvest at INT, while NECB at REF was 6.08 ± 1.74 t C ha−1 including harvest from five grass cuts. Methane fluxes were negligible at both sites. Nitrous oxide emissions dominated the GHG balance at INT. With 144.5 ± 45.5 kg N2O–N ha–1 a–1, they were much higher than at REF (3.9 ± 3.1 kg N2O–N ha–1 a–1) and any other values published so far. Peak fluxes occurred when nitrate concentrations in soil water were extremely high, soil moisture was increased, and vegetation development was struggling. This study highlights the risk of grassland renewals on peat soils regarding yield losses as well as high GHG emissions.

AB - Drained agriculturally used peatlands are hotspots for greenhouse gas (GHG) emissions, especially carbon dioxide (CO2) and nitrous oxide (N2O). To reduce GHG emissions and simultaneously maintain intensive grassland use, raising water levels by subsurface irrigation (SI) is controversially discussed. Both, intensive grassland use and installations of SI may require grassland renewal. We investigated an experimental intervention site (INT) (SI target water levels: -0.30 m) and a deeply drained reference site (REF), both intensive grassland on deep bog peat. After installation of the SI system, a mechanical grassland renewal took place at INT. At both sites, CO2 (eddy covariance), N2O and methane (manual closed chamber technique) were measured. Additionally, soil water was analyzed for nitrogen species. Here, we report on the initial year of GHG measurements including grassland renewal and rising water levels. Overall, GHG emissions were strongly influenced by grassland renewal at INT. Despite progressively rising water levels, soil moisture in the upper centimeters was low and thus grass growth was slow, resulting in an almost complete loss of harvest. This resulted in a net ecosystem carbon balance (NECB) of 4.64 ± 1.03 t C ha−1 containing only 0.57 ± 0.09 t C ha−1 harvest at INT, while NECB at REF was 6.08 ± 1.74 t C ha−1 including harvest from five grass cuts. Methane fluxes were negligible at both sites. Nitrous oxide emissions dominated the GHG balance at INT. With 144.5 ± 45.5 kg N2O–N ha–1 a–1, they were much higher than at REF (3.9 ± 3.1 kg N2O–N ha–1 a–1) and any other values published so far. Peak fluxes occurred when nitrate concentrations in soil water were extremely high, soil moisture was increased, and vegetation development was struggling. This study highlights the risk of grassland renewals on peat soils regarding yield losses as well as high GHG emissions.

KW - Carbon dioxide

KW - Dairy farming

KW - Grassland renovation

KW - Nitrous oxide

KW - Organic soils

KW - Submerged drains

UR - http://www.scopus.com/inward/record.url?scp=85146643344&partnerID=8YFLogxK

U2 - 10.1016/j.agrformet.2023.109309

DO - 10.1016/j.agrformet.2023.109309

M3 - Article

AN - SCOPUS:85146643344

VL - 331

JO - Agricultural and Forest Meteorology

JF - Agricultural and Forest Meteorology

SN - 0168-1923

M1 - 109309

ER -