We found a match
Your institution may have rights to this item. Sign in to continue.
- Title
Effects of submerged drains and ditch blocking on greenhouse gas emissions from intensively used grasslands on Histosols.
- Authors
Heller, Sebastian; Bräuer, Melanie; Gatersleben, Peter; Dettmann, Ullrich; Tiemeyer, Bärbel
- Abstract
Since the Weichselian late-glacial, mires have emerged in the Northern German Lowland andbecame an integral part of today’s landscape composition. During the last century, increasingcultivation efforts turned the majority of the sprawling bogs and fens into productivegrassland or arable land. The ongoing drainage of these organic soils (Histosols) is stillcommon practice, but promotes substantial land subsidence and turns them into akey source of greenhouse gases (GHG). The project 'SWAMPS’ focuses on bothmaintaining the trafficability for conventional intensive grassland use and the reductionof GHG emissions by managing the groundwater level by submerged drains andblocked ditches. Here, we aim to evaluate the effect of water table management on theemissions of carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4) over twoyears. We set up two field sites on both fen and bog peat in North-Western Germany. Submergeddrains were installed at a distance of 4 to 5 m and with a target ditch level of 45 to 50 cmbelow mean soil surface. On the parcels with blocked ditches, the target ditch level isadjusted at 30 to 35 cm. The control parcels are drained by ditches and/or drainagepipes. The grassland is cut four to five times per year and fertilized accordingly.Diurnal CO2 flux measurement campaigns are realised once every three to fourweeks with transparent and opaque chambers and a portable gas analyser. CH4 andN2O samples are taken biweekly and additionally more frequently after fertilizerapplication. Due to constraints in the water management, the full potential of managingwater levels could only be realised from the second half of 2017 onwards. Thefirst year (2017) was thus characterized by strong water table fluctuations. In thefollowing year, different water management regimes were fully operational and cleardifferences in water levels could be achieved despite the extremely dry and hotsummer of 2018. Especially at the bog site used as control, emissions of N2O werevery high (up to 20 kg N ha−1 a−1) and thus clearly exceed standard emissionfactors for grassland on organic soils. CH4 fluxes are negligible and correspondto the low water levels compared to natural peatlands. CO2 emissions from thecontrol sites were high, particularly at the bog peat site. At the fen peat site, CO2emissions in 2017 were reduced by 15 and 43 % at the treatments with submergeddrains and blocked ditches, respectively. In strong contrast, CO2 emission fromthe managed bog peat parcels were 48 % (submerged drains) and 29 % (blockedditches) higher than from the control. This might have been caused by removingwater limitation at the very dry control site. However, CO2 emissions during thefirst year (2017) reflect a transition period between antecedent and experimentalconditions and are not representative for a fully operational water management system.Results from 2018 will be presented as well, and measurements will be continued foranother two years to clarify the effects of water management on GHG emissions.
- Subjects
HISTOSOLS; GREENHOUSE gases; BOGS; GRASSLANDS; DITCHES; GRASSLAND soils; PEAT bogs
- Publication
Geophysical Research Abstracts, 2019, Vol 21, p1
- ISSN
1029-7006
- Publication type
Article