Sub-soil irrigation does not lower greenhouse gas emission from drained peat meadows

Abstract. Current water management in drained peatlands to facilitate agricultural use, leads to soil subsidence and strongly increases greenhouse gas (GHG) emission. High-density, sub-soil irrigation/drainage systems have been proposed as a potential climate mitigation measure, while maintaining high biomass production. In summer, sub-soil irrigation can potentially reduce peat decomposition by preventing groundwater tables to drop below −60 cm. In 2017–2018, we evaluated the effects of sub-soil irrigation on GHG emissions (CO2, CH4, N2O) for four dairy farms on drained peat meadows in the Netherlands. Each farm had a treatment site with perforated pipes at 70 cm below soil level spacing 5–6 m to improve both drainage (winter- spring) and irrigation (summer) of the subsoil, and a control site drained only by ditches (ditch water level −60/−90 cm, 100 m distance between ditches). GHG emissions were measured using closed chambers (0.8 x 0.8 m) every 2–4 weeks. C inputs by manure and C export by grass yields were accounted for. Unexpectedly, sub-soil irrigation hardly affected ecosystem respiration (Reco) despite raising summer groundwater tables (GWT) by 6–18 cm, and even up to 50 cm during drought. Only when the groundwater table of sub-soil irrigation sites was substantially higher than the control value (> 20 cm), Reco was significantly lower (p<0.01), indicating a small effect of irrigation on C turnover. During wet conditions sub-soil pipes lowered water levels by 1–20 cm, without a significant effect on Reco. As a result, Reco differed little (>3 %) between sub-soil irrigation and control sites on an annual base. CO2 fluxes were high at all locations, exceeding 45 t CO2 ha−1a−1, even where peat was covered by clay (25–40 cm). Despite extended drought episodes and lower water levels in 2018, we found lower annual CO2 fluxes than in 2017 indicating drought stress for microbial respiration. Contrary to our expectation, there was no difference between the yearly greenhouse balance of the sub-soil irrigated (64 t CO2–eq ha−1yr−1 in 2017, 53 in 2018) and control sites (61 t CO2–eq ha−1 yr−1 in 2017, 51 in 2018). Emissions of N2O were lower (3 ± 1 t CO2–eq ha−1 yr−1) in 2017 than in 2018 (5 ± 2 t CO2–eq ha−1 yr−1), without treatment effects. The contribution of CH4 to the total GHG budget was negligible (<0.1 %), with lower GWT favoring CH4 oxidation over its production. Even during the 2018 drought, sub-soil irrigation had only little effect on yields (9.7 vs. 9.1 t DM ha−1yr−1), suggesting that increased GWT failed to increase plant water supply. This indicates that peat oxidation is hardly affected, probably because GWT increase only takes place in deeper soil layers (60–120 cm depth). We conclude that, although our field-scale experimental research revealed substantial differences in summer GWT and timing/intensity of irrigation and drainage, sub-soil irrigation fails to lower annual GHG emission and is unsuitable as a climate mitigation strategy. Future research should focus on potential effects of GWT manipulation in the uppermost organic layers (−30 cm and higher) on GHG emissions from drained peatlands.

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Effect of reed canary grass cultivation on greenhouse gas emission from peat soil at controlled rewetting

Biogeosciences ◽

10.5194/bg-12-595-2015 ◽

2015 ◽

Vol 12 (2) ◽

pp. 595-606 ◽

Cited By ~ 13

Author(s):

S. Karki ◽

L. Elsgaard ◽

P. E. Lærke

Keyword(s):

Land Use ◽

Greenhouse Gas ◽

Ecosystem Respiration ◽

Water Levels ◽

Bioenergy Crops ◽

N2o Emissions ◽

Reed Canary Grass ◽

Ghg Emission ◽

Ch4 Emissions ◽

Canary Grass

Abstract. Cultivation of bioenergy crops in rewetted peatland (paludiculture) is considered as a possible land use option to mitigate greenhouse gas (GHG) emissions. However, bioenergy crops like reed canary grass (RCG) can have a complex influence on GHG fluxes. Here we determined the effect of RCG cultivation on GHG emission from peatland rewetted to various extents. Mesocosms were manipulated to three different ground water levels (GWLs), i.e. 0, −10 and −20 cm below the soil surface in a controlled semi-field facility. Emissions of CO2 (ecosystem respiration, ER), CH4 and N2O from mesocosms with RCG and bare soil were measured at weekly to fortnightly intervals with static chamber techniques for a period of 1 year. Cultivation of RCG increased both ER and CH4 emissions, but decreased the N2O emissions. The presence of RCG gave rise to 69, 75 and 85% of total ER at −20, −10 and 0 cm GWL, respectively. However, this difference was due to decreased soil respiration at the rising GWL as the plant-derived CO2 flux was similar at all three GWLs. For methane, 70–95% of the total emission was due to presence of RCG, with the highest contribution at −20 cm GWL. In contrast, cultivation of RCG decreased N2O emission by 33–86% with the major reductions at −10 and −20 cm GWL. In terms of global warming potential, the increase in CH4 emissions due to RCG cultivation was more than offset by the decrease in N2O emissions at −10 and −20 cm GWL; at 0 cm GWL the CH4 emissions was offset only by 23%. CO2 emissions from ER were obviously the dominant RCG-derived GHG flux, but above-ground biomass yields, and preliminary measurements of gross photosynthetic production, showed that ER could be more than balanced due to the photosynthetic uptake of CO2 by RCG. Our results support that RCG cultivation could be a good land use option in terms of mitigating GHG emission from rewetted peatlands, potentially turning these ecosystems into a sink of atmospheric CO2.

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Effect of reed canary grass cultivation on greenhouse gas emission from peat soil at controlled rewetting

Biogeosciences Discussions ◽

10.5194/bgd-11-13309-2014 ◽

2014 ◽

Vol 11 (9) ◽

pp. 13309-13341

Author(s):

S. Karki ◽

L. Elsgaard ◽

P. E. Lærke

Keyword(s):

Land Use ◽

Greenhouse Gas ◽

Ecosystem Respiration ◽

Water Levels ◽

Bioenergy Crops ◽

N2o Emissions ◽

Reed Canary Grass ◽

Ghg Emission ◽

Ch4 Emissions ◽

Canary Grass

Abstract. Cultivation of bioenergy crops in rewetted peatland (paludiculture) is considered as a possible land use option to mitigate greenhouse gas (GHG) emissions. However, bioenergy crops like reed canary grass (RCG) can have a complex influence on GHG fluxes. Here we determined the effect of RCG cultivation on GHG emission from peatland rewetted to various extents. Mesocosms were manipulated to three different ground water levels (GWL), i.e., 0, −10 and −20 cm below the soil surface in a controlled semi-field facility. Emissions of CO2 (ecosystem respiration, ER), CH4 and N2O from mesocosms with RCG and bare soil were measured at weekly to fortnightly intervals with static chamber techniques for a period of one year. Cultivation of RCG increased both ER and CH4 emissions, but decreased the N2O emissions. The presence of RCG gave rise to 69, 75 and 85% of total ER at −20, −10 and 0 cm GWL, respectively However, this difference was due to decreased soil respiration at the rising GWL as the plant-derived CO2 flux was similar at all three GWL. For methane, 70–95% of the total emission was due to presence of RCG, with the highest contribution at −20 cm GWL. In contrast, cultivation of RCG decreased N2O emission by 33–86% with the major reductions at −10 and −20 cm GWL. In terms of global warming potential, the increase in CH4 emissions due to RCG cultivation was more than off-set by the decrease in N2O emissions at −10 and −20 cm GWL; at 0 cm GWL the CH4 emissions was offset only by 23%. CO2 emissions from ER obviously were the dominant RCG-derived GHG flux, but above-ground biomass yields, and preliminary measurements of gross photosynthetic production, show that ER could be more than balanced due to the uptake of CO2 by RCG. Our results support that RCG cultivation could be a good land use option in terms of mitigating GHG emission from rewetted peatlands, potentially turning these ecosystems into a sink of atmospheric CO2.

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Conventional subsoil irrigation techniques do not lower carbon emissions from drained peat meadows

Biogeosciences ◽

10.5194/bg-18-3881-2021 ◽

2021 ◽

Vol 18 (12) ◽

pp. 3881-3902

Author(s):

Stefan Theodorus Johannes Weideveld ◽

Weier Liu ◽

Merit van den Berg ◽

Leon Peter Maria Lamers ◽

Christian Fritz

Keyword(s):

Large Scale ◽

Ecosystem Respiration ◽

Ghg Emissions ◽

Control Site ◽

Future Research ◽

Strong Increase ◽

Climate Mitigation ◽

Soil Subsidence ◽

Significant Difference ◽

And Control

Abstract. The focus of current water management in drained peatlands is to facilitate optimal drainage, which has led to soil subsidence and a strong increase in greenhouse gas (GHG) emissions. The Dutch land and water authorities proposed the application of subsoil irrigation (SSI) system on a large scale to potentially reduce GHG emissions, while maintaining high biomass production. Based on model results, the expectation was that SSI would reduce peat decomposition in summer by preventing groundwater tables (GWTs) from dropping below −60 cm. In 2017–2018, we evaluated the effects of SSI on GHG emissions (CO2, CH4, N2O) for four dairy farms on drained peat meadows in the Netherlands. Each farm had a treatment site with SSI installation and a control site drained only by ditches (ditch water level −60 / −90 cm, 100 m distance between ditches). The SSI system consisted of perforated pipes −70 cm from surface level with spacing of 5–6 m to improve drainage during winter–spring and irrigation in summer. GHG emissions were measured using closed chambers every 2–4 weeks for CO2, CH4 and N2O. Measured ecosystem respiration (Reco) only showed a small difference between SSI and control sites when the GWT of SSI sites were substantially higher than the control site (> 20 cm difference). Over all years and locations, however, there was no significant difference found, despite the 6–18 cm higher GWT in summer and 1–20 cm lower GWT in wet conditions at SSI sites. Differences in mean annual GWT remained low (< 5 cm). Direct comparison of measured N2O and CH4 fluxes between SSI and control sites did not show any significant differences. CO2 fluxes varied according to temperature and management events, while differences between control and SSI sites remained small. Therefore, there was no difference between the annual gap-filled net ecosystem exchange (NEE) of the SSI and control sites. The net ecosystem carbon balance (NECB) was on average 40 and 30 t CO2 ha−1 yr−1 in 2017 and 2018 on the SSI sites and 38 and 34 t CO2 ha−1 yr−1 in 2017 and 2018 on the control sites. This lack of SSI effect is probably because the GWT increase remains limited to deeper soil layers (60–120 cm depth), which contribute little to peat oxidation. We conclude that SSI modulates water table dynamics but fails to lower annual carbon emission. SSI seems unsuitable as a climate mitigation strategy. Future research should focus on potential effects of GWT manipulation in the uppermost organic layers (−30 cm and higher) on GHG emissions from drained peatlands.

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Agricultural Greenhouse Gas Emissions: Knowledge and Positions of German Farmers

Land ◽

10.3390/land9050130 ◽

2020 ◽

Vol 9 (5) ◽

pp. 130

Author(s):

Kerstin Jantke ◽

Martina J. Hartmann ◽

Livia Rasche ◽

Benjamin Blanz ◽

Uwe A. Schneider

Keyword(s):

Greenhouse Gas ◽

Online Survey ◽

Agricultural Sector ◽

Ghg Emissions ◽

Mitigation Measures ◽

Climate Mitigation ◽

Sufficient Information ◽

Ghg Emission ◽

Personal Motivation ◽

Further Development

Climate mitigation targets must involve the agricultural sector, which contributes 10%–14% of global anthropogenic greenhouse gas (GHG) emissions. To evaluate options for implementing mitigation measures in the agricultural sector, farmers’ knowledge, positions, and attitudes towards agricultural GHG emissions, their accounting, and reduction need to be understood. Using an online survey, we asked 254 German farmers about their motivation to reduce GHG emissions and their acceptance of possible regulation schemes. We examined differences between relevant farming sectors, i.e., conventional versus organic and livestock keeping versus crop-cultivating farms. Results show that German farmers are aware of climatic changes and feel a general commitment to reducing GHG emissions but lack sufficient information. We identified agricultural magazines as the most effective tool for disseminating relevant knowledge. German farmers would feel motivated to adopt climate-friendly farming styles if products were labeled accordingly and if they received subsidies and public acknowledgment for their effort. As long as there is no regulation of agricultural GHGs through taxes or subsidies, personal motivation is yet the strongest motivation for voluntary emission reduction. Our findings are timely for the further development of strategies and instruments that reduce agricultural GHG emission and account for the farmers’ views. The dataset is available for further investigations.

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Remotely sensed temperature is a proxy of greenhouse gas emissions in intact and managed peatlands

10.5194/egusphere-egu21-4474 ◽

2021 ◽

Author(s):

Ain Kull ◽

Iuliia Burdun ◽

Gert Veber ◽

Oleksandr Karasov ◽

Martin Maddison ◽

...

Keyword(s):

Soil Temperature ◽

Greenhouse Gas Emissions ◽

Greenhouse Gas ◽

Water Table ◽

Ecosystem Respiration ◽

Ghg Emissions ◽

Remotely Sensed ◽

Water Table Depth ◽

Gas Emissions

Besides water table depth, soil temperature is one of the main drivers of greenhouse gas (GHG) emissions in intact and managed peatlands. In this work, we evaluate the performance of remotely sensed land surface temperature (LST) as a proxy of greenhouse gas emissions in intact, drained and extracted peatlands. For this, we used chamber-measured carbon dioxide (CO2) and methane (CH4) data from seven peatlands in Estonia collected during vegetation season in 2017&#8211;2020. Additionally, we used temperature and water table depth data measured in situ. We studied relationships between CO2, CH4, in-situ parameters and remotely sensed LST from Landsat 7 and 8, and MODIS Terra. Results of our study suggest that LST has stronger relationships with surface and soil temperature as well as with ecosystem respiration (Reco) over drained and extracted sites than over intact ones. Over the extracted cites the correlation between Reco CO2 and LST is 0.7, and over the drained sites correlation is 0.5. In natural sites, we revealed a moderate positive relationship between LST and CO2 emitted in hollows (correlation is 0.6) while it is weak in hummocks (correlation is 0.3). Our study contributes to the better understanding of relationships between greenhouse gas emissions and their remotely sensed proxies over peatlands with different management status and enables better spatial assessment of GHG emissions in drainage affected northern temperate peatlands.

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Greenhouse gas budget of an extensively managed grassland on drained peat soil in the Irish Midlands

10.5194/egusphere-egu21-10285 ◽

2021 ◽

Author(s):

Marine Valmier ◽

Matthew Saunders ◽

Gary Lanigan

Keyword(s):

Carbon Source ◽

Greenhouse Gas ◽

Ghg Emissions ◽

Organic Soils ◽

Climate Mitigation ◽

Sink Strength ◽

Management Options ◽

Peat Soils ◽

Sequestration Potential ◽

Sink Capacity

Grassland-based agriculture in Ireland contributes over one third of national greenhouse gas (GHG) emissions, and the LULUCF sector is a net GHG source primarily due to the ongoing drainage of peat soils. Rewetting of peat-based organic soils is now recognised as an attractive climate mitigation strategy, but reducing emissions and restoring the carbon sequestration potential is challenging, and is not always feasible notably due to agricultural demands. Nonetheless, reducing carbon losses from drained organic soils has been identified as a key action for Ireland to reach its climate targets, and carbon storage associated with improved grassland management practices can provide a suitable strategy to offset GHG emissions without compromising productivity. However, research is still needed to assess the best practices and management options for optimum environmental and production outcomes. While grasslands have been widely studied internationally, data on organic soils under this land use are still scarce. In Ireland, despite their spatial extent and relevance to the national emission inventories and mitigation strategies, only two studies on GHG emissions from grasslands on peat soils have been published.Here we present results from a grassland on a drained organic soil that is extensively managed for silage production in the Irish midlands. Continuous monitoring of Net Ecosystem Exchange (NEE) of carbon dioxide (CO2) using eddy covariance techniques, and weekly static chamber measurements to assess soil derived emissions of methane (CH4) and nitrous oxide (N2O) started in 2020. The seasonal CO2 fluxes observed were greatly dependent on weather conditions and management events. The grassland shifted from a carbon source at the beginning of the year to a sink during the growing season, with carbon uptakes in April and May ranging from 15 to 40 &#181;mol CO2 m-2 s-1 and releases in the order of 5 &#181;mol CO2 m-2 s-1. Following the first harvest event in early June, approximately 2.5 t C ha-1 was exported, and the sink capacity took around one month to recover, with an average NEE of 10 &#181;mol CO2 m-2 s-1 during that period. Carbon uptake then reached a maximum of 25 &#181;mol CO2 m-2 s-1 in August. After the second cut in mid-September, which corresponded to an export of 2.25 t.ha-1 of carbon, the grassland acted once again as a strong carbon source, losing almost 30 g C m-2 in a month, before stabilising and behaving as an overall small source during the winter period.In summary, this grassland demonstrated high rates of carbon assimilation and productivity that translate in a strong carbon sink capacity highly dependent on the management. The biomass harvest is a major component of the annual budget that has the potential to shift the system to a net carbon source. Moreover, while initial measurements of CH4 and N2O fluxes appeared to be negligible, some management events were not assessed due to national COVID 19 restrictions on movement, which might have impacted the sink strength of the site studied.

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Trade-offs between high yields and greenhouse gas emissions in irrigation wheat cropland in China

Biogeosciences ◽

10.5194/bg-11-2287-2014 ◽

2014 ◽

Vol 11 (8) ◽

pp. 2287-2294 ◽

Cited By ~ 12

Author(s):

Z. L. Cui ◽

L. Wu ◽

Y. L. Ye ◽

W. Q. Ma ◽

X. P. Chen ◽

...

Keyword(s):

Winter Wheat ◽

Grain Yield ◽

Greenhouse Gas ◽

Ghg Emissions ◽

Triticum Aestivum L ◽

Ghg Emission ◽

Trade Off ◽

Trade Offs ◽

High Yields ◽

Scientific Attention

Abstract. Although the concept of producing higher yields with reduced greenhouse gas (GHG) emissions is a goal that attracts increasing public and scientific attention, the trade-off between high yields and GHG emissions in intensive agricultural production is not well understood. Here, we hypothesize that there exists a mechanistic relationship between wheat grain yield and GHG emission, and that could be transformed into better agronomic management. A total 33 sites of on-farm experiments were investigated to evaluate the relationship between grain yield and GHG emissions using two systems (conventional practice, CP; high-yielding systems, HY) of intensive winter wheat (Triticum aestivum L.) in China. Furthermore, we discussed the potential to produce higher yields with lower GHG emissions based on a survey of 2938 farmers. Compared to the CP system, grain yield was 39% (2352 kg ha−1) higher in the HY system, while GHG emissions increased by only 10%, and GHG emission intensity was reduced by 21%. The current intensive winter wheat system with farmers' practice had a median yield and maximum GHG emission rate of 6050 kg ha−1 and 4783 kg CO2 eq ha−1, respectively; however, this system can be transformed to maintain yields while reducing GHG emissions by 26% (6077 kg ha−1, and 3555 kg CO2 eq ha−1). Further, the HY system was found to increase grain yield by 39% with a simultaneous reduction in GHG emissions by 18% (8429 kg ha−1, and 3905 kg CO2 eq ha−1, respectively). In the future, we suggest moving the trade-off relationships and calculations from grain yield and GHG emissions to new measures of productivity and environmental protection using innovative management technologies.

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Effects of topsoil removal on greenhouse gas exchange of fen paludicultures

10.5194/egusphere-egu21-12939 ◽

2021 ◽

Author(s):

Philipp-Fernando Köwitsch ◽

Bärbel Tiemeyer

Keyword(s):

Gas Exchange ◽

Greenhouse Gas ◽

Ghg Emissions ◽

Typha Latifolia ◽

Phosphorus Release ◽

Water Levels ◽

Conventional Agriculture ◽

Topsoil Removal ◽

Productive Land ◽

The One

Drainage is necessary for conventional agriculture on peatlands, but this practice causes high emissions of the greenhouse gases (GHG) carbon dioxide and nitrous oxide. Paludiculture is an option to mitigate these adverse environmental effects while maintaining productive land use. Whereas the GHG exchange of paludiculture on rewetted bog peat, i.e. Sphagnum farming, is relatively well examined, data on GHG emissions from fen paludicultures is still very scarce. As typical fen paludiculture species are all aerenchymous plants, the release of methane is of particular interest when optimising the GHG balance of such systems. Topsoil removal is, on the one hand, an option to reduce methane emissions as well as phosphorus release upon rewetting, but on the other hand, nutrient-rich topsoils might foster biomass growth.In this project, Typha angustifolia, Typha latifolia, and Phragmites australis are grown at a fen peatland formerly used as grassland. Water levels will be kept at the surface or slightly above it. In parts of the newly created polder, the topsoil will be removed. To be able to separate the effects of topsoil removal and water level, four smaller sub-polders will be installed. Greenhouse gas exchange will be measured with closed manual chambers for all three species with and without topsoil removal as well as at a reference grassland site close by.

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A Rough Set Based Assessment of the Strategies to Reduce Greenhouse Gas Emissions: A Tanzanian Shipping Sector Perspective

Advances in Decision Sciences ◽

10.1155/2016/8256072 ◽

2016 ◽

Vol 2016 ◽

pp. 1-11

Author(s):

Erick P. Massami ◽

Benitha M. Myamba

Keyword(s):

Greenhouse Gas ◽

Rough Set ◽

Statistical Data ◽

Ghg Emissions ◽

Ghg Emission ◽

Sea Transport ◽

Abatement Strategies ◽

Reduction Strategies ◽

Emission Reduction Strategies ◽

Synthetic Assessment

The Greenhouse Gas (GHG) emissions due to transport operations have drastically increased in recent years. The sea transport in particular contributes 2.7 to 3 percent of CO2, a major component of GHG emissions globally. Numerous measures have been undertaken locally and internationally to alleviate the sea transport share of Greenhouse Gases. However, most of these measures will be fruitful if ship investors (e.g., ship owners and operators) would fully employ the GHG emission reduction strategies. Due to the scarcity of the statistical data in this respect, this study therefore presents a rough set synthetic assessment (RSSA) model to GHG emission abatement strategies in the Tanzanian shipping sector. The results of the assessment reveal that the Tanzanian shipping companies engaged in Cabotage trade are aware of the abatement strategies and moderately apply them.

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First field estimation of greenhouse gas emissions from European soil-dwelling Scarabaeidae larvae targeting the genus Melolontha

10.5194/egusphere-egu2020-19924 ◽

2020 ◽

Author(s):

Carolyn-Monika Görres ◽

Claudia Kammann

Keyword(s):

Greenhouse Gas ◽

Carbon Emissions ◽

Developmental Stages ◽

Ghg Emissions ◽

Field Measurements ◽

Spatial And Temporal Variability ◽

Activity Levels ◽

Ghg Emission ◽

Forest Sites ◽

Wide Range

Arthropods are a major soil fauna group, and have the potential to substantially influence the spatial and temporal variability of soil greenhouse gas (GHG) sinks and sources. The overall effect of soil-inhabiting arthropods on soil GHG fluxes still remains poorly quantified since the majority of the available data comes from laboratory experiments, is often controversial, and has been limited to a few species. The main objective of this study was to provide first insights into field-level carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) emissions of soil-inhabiting larvae of the Scarabaeidae family. Larvae of the genus Melolontha were excavated at various grassland and forest sites in west-central and southern Germany, covering a wide range of different larval developmental stages, and larval activity levels. Excavated larvae were immediately incubated in the field to measure their GHG emissions. Gaseous carbon emissions of individual larvae showed a large inter- and intra-site variability which was strongly correlated to larval biomass. This correlation persisted when upscaling CO2 and CH4 emissions to the plot scale. Field emission estimates for Melolontha spp. were subsequently upscaled to the European level to derive the first regional GHG emission estimates for members of the Scarabaeidae family. Estimates ranged between 10.42 and 409.53 kt CO2 yr-1, and 0.01 and 1.36 kt CH4 yr-1. Larval N2O emissions were only sporadically observed and not upscaled. For one site, a comparison of field- and laboratory-based GHG emission measurements was conducted to assess potential biases introduced by transferring Scarabaeidae larvae to artificial environments. Emission strength and variability of captive larvae decreased significantly within two weeks and the correlation between larval biomass and gaseous carbon emissions disappeared, highlighting the importance of field measurements. Overall, our data show that Scarabaeidae larvae can be significant soil GHG sources and should not be neglected in soil GHG flux research.

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