TY - JOUR

T1 - Effects of water management and grassland renewal on the greenhouse gas emissions from intensively used grassland on bog peat

AU - Tiemeyer, Bärbel

AU - Oehmke, Willi

AU - Gatersleben, Peter

AU - Bräuer, Melanie

AU - Dettmann, Ullrich

AU - Heller, Sebastian

N1 - Funding Information: We are grateful for the financial support of the project “SWAMPS” 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 (ZW-85003757). Our gas chromatography laboratory (Roland Fuß, Daniel Ziehe, Andrea Oehns-Rittgerodt and Kerstin Gilke) analysed the gas samples, while the central laboratory (Nicole Altwein, Ines Backwinkel, Ute Tambor) and the laboratory for soil monitoring (Arne Heidkamp) were invaluable for soil chemical and biomass analyses. We also want to express our thanks to Thomas Viohl for soil physical analyses. The extensive field work in this project would not have been possible without the support of Dirk Lempio, Frank Hegewald, Marc Jantz, Thomas Viohl, Lena Barczyk, Katja Braun, Annalisa del Ben, Johannes Eltzsch, Jessica Hügen and Julia Zenner as well as the Peatland Research Group of the Thünen Institute of Climate-Smart Agriculture. We also express our thanks to our project partners. Further, two anonymous reviewers helped to improve the manuscript by their insightful comments. Finally, the project would not have been possible without the farmer who granted us access to their field and provided us with all the necessary information and support to conduct our study.

PY - 2024/2/15

Y1 - 2024/2/15

N2 - Artificial drainage is prerequisite for conventional agricultural use of peatlands, but causes high emissions of greenhouse gases (GHG), mainly carbon dioxide (CO2). Furthermore, grassland renewal is regularly practiced to maintain high fodder quality, but might cause high emissions of nitrous oxide (N2O). Raising water levels is necessary to reduce CO2 emissions. Water management by subsurface irrigation (SI) and ditch blocking (DB) is thus discussed as potential compromise between maintaining intensive grassland use and reducing GHG emissions. Here, we present results of a four year study on the effects of SI and DB in combination with grassland renewal on GHG emissions from an intensively used grassland on bog peat in North-Western Germany. The water management itself was successful and lead to average mean annual water levels of -0.33 m at the parcels with SI. This was 0.38 m higher than at the control parcels. Ditch blocking also raised the mean water levels to -0.33 m, but the parcel was dryer in summer and wetter in spring than those with SI. Despite clear effects on water levels, CO2 and total GHG emissions were much (38 % and 31 %) higher from SI parcels than from the control parcels. CO2 and GHG emissions of the DB parcel were similar to those of the control. Shallow ploughing increased N2O emissions for around 1.5 years, but there was no clear effect of direct sowing. Methane emission from all parcels were low. The surprising results regarding CO2 might be explained by an interaction of increased soil moisture in the topsoil and improved nutrient retention during periods of high soil temperatures facilitated by SI and, concurrently, by limitations of microbial activity due to dry conditions at the control parcels. Thus, results of this study do not support subsurface irrigation as a GHG mitigation measure at intensively used bog peatlands.

AB - Artificial drainage is prerequisite for conventional agricultural use of peatlands, but causes high emissions of greenhouse gases (GHG), mainly carbon dioxide (CO2). Furthermore, grassland renewal is regularly practiced to maintain high fodder quality, but might cause high emissions of nitrous oxide (N2O). Raising water levels is necessary to reduce CO2 emissions. Water management by subsurface irrigation (SI) and ditch blocking (DB) is thus discussed as potential compromise between maintaining intensive grassland use and reducing GHG emissions. Here, we present results of a four year study on the effects of SI and DB in combination with grassland renewal on GHG emissions from an intensively used grassland on bog peat in North-Western Germany. The water management itself was successful and lead to average mean annual water levels of -0.33 m at the parcels with SI. This was 0.38 m higher than at the control parcels. Ditch blocking also raised the mean water levels to -0.33 m, but the parcel was dryer in summer and wetter in spring than those with SI. Despite clear effects on water levels, CO2 and total GHG emissions were much (38 % and 31 %) higher from SI parcels than from the control parcels. CO2 and GHG emissions of the DB parcel were similar to those of the control. Shallow ploughing increased N2O emissions for around 1.5 years, but there was no clear effect of direct sowing. Methane emission from all parcels were low. The surprising results regarding CO2 might be explained by an interaction of increased soil moisture in the topsoil and improved nutrient retention during periods of high soil temperatures facilitated by SI and, concurrently, by limitations of microbial activity due to dry conditions at the control parcels. Thus, results of this study do not support subsurface irrigation as a GHG mitigation measure at intensively used bog peatlands.

KW - Chamber method

KW - Greenhouse gases

KW - Nitrogen

KW - Peatland

KW - Phosphorus

KW - Water management

UR - http://www.scopus.com/inward/record.url?scp=85180498475&partnerID=8YFLogxK

U2 - 10.1016/j.agrformet.2023.109858

DO - 10.1016/j.agrformet.2023.109858

M3 - Article

AN - SCOPUS:85180498475

VL - 345

JO - Agricultural and Forest Meteorology

JF - Agricultural and Forest Meteorology

SN - 0168-1923

M1 - 109858

ER -