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

Author(s):  
Marine Valmier ◽  
Matthew Saunders ◽  
Gary Lanigan

<p>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.</p><p>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 (CO<sub>2</sub>) using eddy covariance techniques, and weekly static chamber measurements to assess soil derived emissions of methane (CH<sub>4</sub>) and nitrous oxide (N<sub>2</sub>O) started in 2020. The seasonal CO<sub>2</sub> 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 µmol CO<sub>2</sub> m<sup>-2</sup> s<sup>-1</sup> and releases in the order of 5 µmol CO<sub>2</sub> m<sup>-2</sup> s<sup>-1</sup>. Following the first harvest event in early June, approximately 2.5 t C ha<sup>-1</sup> was exported, and the sink capacity took around one month to recover, with an average NEE of 10 µmol CO<sub>2</sub> m<sup>-2</sup> s<sup>-1</sup> during that period. Carbon uptake then reached a maximum of 25 µmol CO<sub>2</sub> m<sup>-2</sup> s<sup>-1</sup> in August. After the second cut in mid-September, which corresponded to an export of 2.25 t.ha<sup>-1</sup> of carbon, the grassland acted once again as a strong carbon source, losing almost 30 g C m<sup>-2</sup> in a month, before stabilising and behaving as an overall small source during the winter period.</p><p>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 CH<sub>4</sub> and N<sub>2</sub>O 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.</p>

FACETS ◽  
2021 ◽  
Vol 6 (1) ◽  
pp. 334-357
Author(s):  
Robert Newell ◽  
Lenore Newman ◽  
Mathew Dickson ◽  
Bill Vanderkooi ◽  
Tim Fernback ◽  
...  

This research explores the potential hydroponic systems have for contributing to climate mitigation in fodder agriculture. Using British Columbia (BC) and Alberta as case studies, the study compares greenhouse gas (GHG) emissions and carbon sequestration potential of hydroponically grown sprouted barley fodder to conventional barley grain fodder. GHG emissions were examined through scenarios that assumed Alberta to be the main barley producer, while exploring different situations of BC and Alberta as consumers, distributed/centralized hydroponic systems, and renewable/nonrenewable energy. Carbon sequestration opportunities were examined through scenarios that explored the land sparing potential of transitioning from conventional to hydroponic barley and shifts from tillage to no-tillage practices. Sensitivity analyses were done to examine how changes in hydroponic seed-to-fodder output and energy consumption affect the systems’ climate mitigation potential. The results indicated that incorporating hydroponic systems into barley production has the potential to reduce GHG emissions, given seed-to-fodder output and energy consumption are maintained at certain levels and the systems are powered by renewable energy. Results also showed that hydroponic farming can provide greater carbon sequestration opportunities than simply shifting to no-tillage farming. The research indicates that hydroponic fodder farming could contribute to climate mitigation objectives if complemented with effective energy and land use policies.


2021 ◽  
Author(s):  
Sylvia Vetter ◽  
Michael Martin ◽  
Pete Smith

<p>Reducing greenhouse gas (GHG) emissions in to the atmosphere to limit global warming is the big challenge of the coming decades. The focus lies on negative emission technologies to remove GHGs from the atmosphere from different sectors. Agriculture produces around a quarter of all the anthropogenic GHGs globally (including land use change and afforestation). Reducing these net emissions can be achieved through techniques that increase the soil organic carbon (SOC) stocks. These techniques include improved management practices in agriculture and grassland systems, which increase the organic carbon (C) input or reduce soil disturbances. The C sequestration potential differs among soils depending on climate, soil properties and management, with the highest potential for poor soils (SOC stock farthest from saturation).</p><p>Modelling can be used to estimate the technical potential to sequester C of agricultural land under different mitigation practices for the next decades under different climate scenarios. The ECOSSE model was developed to simulate soil C dynamics and GHG emissions in mineral and organic soils. A spatial version of the model (GlobalECOSSE) was adapted to simulate agricultural soils around the world to calculate the SOC change under changing management and climate.</p><p>Practices like different tillage management, crop rotations and residue incorporation showed regional differences and the importance of adapting mitigation practices under an increased changing climate. A fast adoption of practices that increase SOC has its own challenges, as the potential to sequester C is high until the soil reached a new C equilibrium. Therefore, the potential to use soil C sequestration to reduce overall GHG emissions is limited. The results showed a high potential to sequester C until 2050 but much lower rates in the second half of the century, highlighting the importance of using soil C sequestration in the coming decades to reach net zero by 2050.</p>


2021 ◽  
Author(s):  
Saara Lind ◽  
Marja Maljanen ◽  
Merja Myllys ◽  
Mari Räty ◽  
Sanna Kykkänen ◽  
...  

<p>Agricultural soils are a significant source of greenhouse gas (GHG) emissions. To study these emissions, we are currently building three research platforms that consist of full eddy covariance instrumentation for determination of net ecosystem carbon dioxide exchange and fluxes of methane and nitrous oxide. These platforms will be completed with supporting weather, plant and soil data collection. Two of our platforms are sites on organic soils with a thick peat layer (>60 cm) and the third one is on a mineral soil (silt loam). To study the role of the grassland management practises at these sites, we have initiated ORMINURMI-project. Here, we will characterise the effects of ground water table (high vs. low), crop renewal methods (autumn vs. summer) and plant species (tall fescue vs. red glover grass) on greenhouse gas budgets of grass production. Also effect on yield amount and nutrient quality will be determined. In this presentation, we will present the preliminary data collected at these research platforms and our plans for the use of these data in the coming years.</p>


2008 ◽  
Vol 58 (11) ◽  
pp. 2093-2099 ◽  
Author(s):  
Robert Wilcock ◽  
Sandy Elliott ◽  
Neale Hudson ◽  
Stephanie Parkyn ◽  
John Quinn

New Zealand is unique in that half of its national greenhouse gas (GHG) inventory derives from agriculture - predominantly as methane (CH4) and nitrous oxide (N2O), in a 2:1 ratio. The remaining GHG emissions predominantly comprise carbon dioxide (CO2) deriving from energy and industry sources. Proposed strategies to mitigate emissions of CH4 and N2O from pastoral agriculture in New Zealand are: (1) utilising extensive and riparian afforestation of pasture to achieve CO2 uptake (carbon sequestration); (2) management of nitrogen through budgeting and/or the use of nitrification inhibitors, and minimizing soil anoxia to reduce N2O emissions; and (3) utilisation of alternative waste treatment technologies to minimise emissions of CH4. These mitigation measures have associated co-benefits and co-costs (disadvantages) for rivers, streams and lakes because they affect land use, runoff loads, and receiving water and habitat quality. Extensive afforestation results in lower specific yields (exports) of nitrogen (N), phosphorus (P), suspended sediment (SS) and faecal matter and also has benefits for stream habitat quality by improving stream temperature, dissolved oxygen and pH regimes through greater shading, and the supply of woody debris and terrestrial food resources. Riparian afforestation does not achieve the same reductions in exports as extensive afforestation but can achieve reductions in concentrations of N, P, SS and faecal organisms. Extensive afforestation of pasture leads to reduced water yields and stream flows. Both afforestation measures produce intermittent disturbances to waterways during forestry operations (logging and thinning), resulting in sediment release from channel re-stabilisation and localised flooding, including formation of debris dams at culverts. Soil and fertiliser management benefits aquatic ecosystems by reducing N exports but the use of nitrification inhibitors, viz. dicyandiamide (DCD), to achieve this may under some circumstances impair wetland function to intercept and remove nitrate from drainage water, or even add to the overall N loading to waterways. DCD is water soluble and degrades rapidly in warm soil conditions. The recommended application rate of 10 kg DCD/ha corresponds to 6 kg N/ha and may be exceeded in warm climates. Of the N2O produced by agricultural systems, approximately 30% is emitted from indirect sources, which are waterways draining agriculture. It is important therefore to focus strategies for managing N inputs to agricultural systems generally to reduce inputs to wetlands and streams where these might be reduced to N2O. Waste management options include utilizing the CH4 resource produced in farm waste treatment ponds as a source of energy, with conversion to CO2 via combustion achieving a 21-fold reduction in GHG emissions. Both of these have co-benefits for waterways as a result of reduced loadings. A conceptual model derived showing the linkages between key land management practices for greenhouse gas mitigation and key waterway values and ecosystem attributes is derived to aid resource managers making decisions affecting waterways and atmospheric GHG emissions.


2022 ◽  
Vol 5 ◽  
Author(s):  
Megan Reavis ◽  
Jenny Ahlen ◽  
Joe Rudek ◽  
Kusum Naithani

The dramatic increase in greenhouse gas (GHG) emissions by humans over the past century and a half has created an urgency for monitoring, reporting, and verifying GHG emissions as a first step toward mitigating the effects of climate change. Fifteen percent of global GHG emissions come from agriculture, and companies in the food and beverage industry are starting to set climate goals. We examined the GHG emissions reporting practices and climate goals of the top 100 global food and beverage companies (as ranked by Food Engineering) and determined whether their goals are aligned with the science of keeping climate warming well below a 2°C increase. Using publicly disclosed data in CDP Climate reports and company sustainability reports, we found that about two thirds of the top 100 global food and beverage companies disclose at least part of their total company emissions and set some sort of climate goal that includes scope 1 and 2 emissions. However, only about half have measured, disclosed, and set goals for scope 3 emissions, which often encompass about 88% of a company's emissions across the entire value chain on average. We also determined that companies, despite setting scope 1, 2, and 3 emission goals, may be missing the mark on whether their goals are significantly reducing global emissions. Our results present the current disclosure and emission goals of the top 100 global food and beverage companies and highlight an urgent need to begin and continue to set truly ambitious, science-aligned climate goals.


2007 ◽  
Vol 363 (1492) ◽  
pp. 789-813 ◽  
Author(s):  
Pete Smith ◽  
Daniel Martino ◽  
Zucong Cai ◽  
Daniel Gwary ◽  
Henry Janzen ◽  
...  

Agricultural lands occupy 37% of the earth's land surface. Agriculture accounts for 52 and 84% of global anthropogenic methane and nitrous oxide emissions. Agricultural soils may also act as a sink or source for CO 2 , but the net flux is small. Many agricultural practices can potentially mitigate greenhouse gas (GHG) emissions, the most prominent of which are improved cropland and grazing land management and restoration of degraded lands and cultivated organic soils. Lower, but still significant mitigation potential is provided by water and rice management, set-aside, land use change and agroforestry, livestock management and manure management. The global technical mitigation potential from agriculture (excluding fossil fuel offsets from biomass) by 2030, considering all gases, is estimated to be approximately 5500–6000 Mt CO 2 -eq. yr −1 , with economic potentials of approximately 1500–1600, 2500–2700 and 4000–4300 Mt CO 2 -eq. yr −1 at carbon prices of up to 20, up to 50 and up to 100 US$ t CO 2 -eq. −1 , respectively. In addition, GHG emissions could be reduced by substitution of fossil fuels for energy production by agricultural feedstocks (e.g. crop residues, dung and dedicated energy crops). The economic mitigation potential of biomass energy from agriculture is estimated to be 640, 2240 and 16 000 Mt CO 2 -eq. yr −1 at 0–20, 0–50 and 0–100 US$ t CO 2 -eq. −1 , respectively.


2015 ◽  
Vol 31 (3) ◽  
pp. 191-201 ◽  
Author(s):  
Christine Costello ◽  
Esma Birisci ◽  
Ronald G. McGarvey

AbstractThere are many economic, social and environmental reasons to reduce the occurrence of food that is wasted. As communities consider options for managing their food waste streams, an understanding of the volume, composition and variability of these streams is needed to inform the decision-making process and potentially justify the capital investments needed for separation and treatment operations. This more detailed inventory also allows for the estimation of embodied resources in food that is wasted, demonstrated herein for greenhouse gas emissions (GHGs). Pre- and post-consumer food waste was collected from four all-you-care-to-eat Campus Dining Services (CDS) facilities at the University of Missouri, Columbia over 3 months in 2014. During the study period approximately 246.3 metric tons (t) of food reached the retail level at the four facilities. 232.4 t of this food was served and 13.9 t of it (10.1 t of edible and 3.8 t of inedible), was lost as pre-consumer waste. Over the same time period, an estimated 26.4 t of post-consumer food waste was generated at these facilities, 21.2 t of the waste edible and 5.3 t of it inedible. Overall, 5.6% of food reaching the retail level was lost at the pre-consumer stage and 10.7% was lost at the post-consumer stage. Out of the food categories examined, ‘fruits and vegetables’ constituted the largest source of food waste by weight, with grains as the second largest source of food waste by weight. GHGs embodied in edible food waste were calculated. Over the study period an estimated 11.1 t CO2e (100-yr) were embodied in the pre-consumer food waste and 56.1 t were embodied in post-consumer food waste for a total of 67.2 t. The ‘meat and protein’ category represents the largest embodiment of GHG emissions in both the pre- and post-consumer categories despite ranking fourth in total weight. Beef represents the largest contribution to post-consumer GHG emissions embodied in food waste with an estimated 34.1 t CO2e. This distinction between the greatest sources of food waste by weight and the greatest sources of GHG emissions is relevant when considering alternative management options for food waste.


2021 ◽  
Vol 10 (2) ◽  
pp. 252
Author(s):  
Diah Apriani Atika Sari ◽  
Okid Parama Astirin ◽  
Anti Mayastuti ◽  
Anugrah Adiastuti

<em>Greenhouse Gas (GHG) emissions are the main cause of global warming and climate change. Indonesia as an archipelagic country experiences a significant negative impact as a result of climate change, such as sea level rise, sea water intrusion to the land, extreme weather, and rising sea and land temperatures. Tropical forests have been known as a major carbon emitter, but with the increasing rate of deforestation, it is necessary to find carbon sinks from ecosystems other than tropical forests. This study aimed to determine the extent to which blue carbon has been included in Indonesian Government policies, especially in the GHG inventory document and the Indonesian Nationally Determined Contribution (NDC) document, related to the Government of Indonesia's commitment in reducing GHG emissions. The research showed that blue carbon ecosystems, which include mangroves, seagrass beds, and other coastal ecosystems, have enormous carbon sequestration potential when compared to tropical forests, but unfortunately, the potential of blue carbon has not been maximally utilized in national policies related to GHG emission reduction.</em> <em>The existing policies have not been implemented optimally and some of them overlap. In the future, accurate data updating and mapping of the blue carbon ecosystem is needed so that it can become a reference in determining national policies on the use of blue carbon</em>


2016 ◽  
Vol 34 (2) ◽  
pp. 277-284
Author(s):  
Hernando Criollo E. ◽  
Amanda Silva P. ◽  
Hernando Delgado H.

This research focused on the greenhouse gas (GHG) emissions and potential sinks associated with conventional and sustainable fruit production systems in the Highlands region of Pasto, Nariño, Colombia. Based on the IPCC (2006) methodologies, the annual emission balance for a 6-year production cycle included agricultural sources and gasoline consumption related to the main agricultural activities and the potential for soil C accumulation and biomass C fixation in all of the studied systems. The multivariate analysis showed that positive GHG balance emissions would be achieved in all sustainable fruit production systems, as compared to conventional fruit production systems with greater impact on (SS1): Rubusglaucus Benth. associated with Acacia decurrens trees and live coverage of kikuyu Pen-nisetum clandestinum grass. According to the results of this study, (SS1) showed the beneficial total GHG balance emission accounting for -21,079 kg of atmospheric CO2eq ha-1 yr-1 divided into -4,587 kg CO2eq ha-1 yr-1 and -17,102 kg CO2eq ha-1 yr-1 due an annual soil and biomass C sequestration potential that could help offset its emissions (610 kg CO2eq ha-1 yr-1).


2020 ◽  
Author(s):  
Stefan Theodorus Johannes Weideveld ◽  
Weier Liu ◽  
Merit van den Berg ◽  
Leon Peter Maria Lamers ◽  
Christian Fritz

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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