BG3.35 | Exchange of GHG and reactive gases in agricultural ecosystems
EDI
Exchange of GHG and reactive gases in agricultural ecosystems
Co-organized by SSS9
Convener: Christof Ammann | Co-conveners: Christian Brümmer, Eliza HarrisECSECS, Alexander Moravek, Alex Valach
Orals
| Thu, 18 Apr, 16:15–18:00 (CEST)
 
Room 2.17
Posters on site
| Attendance Thu, 18 Apr, 10:45–12:30 (CEST) | Display Thu, 18 Apr, 08:30–12:30
 
Hall X1
Posters virtual
| Attendance Thu, 18 Apr, 14:00–15:45 (CEST) | Display Thu, 18 Apr, 08:30–18:00
 
vHall X1
Orals |
Thu, 16:15
Thu, 10:45
Thu, 14:00
Managed agricultural ecosystems (grassland and cropland) are an important source and/or sink for greenhouse gases (GHG) as well as for reactive trace gases. Representative measurements and modelling under typical conditions as well as for potential mitigation options are necessary as a basis for recommendations to policy makers and farmers.
Due to the simultaneous influence of various environmental drivers and management activities (e.g. fertilizer application, harvest, grazing) the flux patterns are often complex and difficult to attribute to individual drivers. Moreover, management related mitigation options may often result in trade-offs between different GHG or between emission of GHG and reactive gases like NH3, NOx, or VOCs. To investigate these interactions, the session addresses experimentalists and modelers working on carbon and nitrogen cycling processes and related fluxes on plot, field, landscape, and regional scale. It is open to a wide range of studies including the development and application of new devices, methods, and model approaches as well as field observations and process studies. Particularly welcome are studies on multiple gases and on the full carbon, nitrogen or GHG budgets. We also encourage contributions about the applicability and overall potential of mitigation options.

Orals: Thu, 18 Apr | Room 2.17

Chairpersons: Alex Valach, Christian Brümmer, Eliza Harris
16:15–16:18
16:18–16:28
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EGU24-1586
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ECS
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On-site presentation
Meng Kong, Søren O. Petersen, Jørgen Eriksen, and Christian Dold

The inclusion of grass-clover (GC) leys in crop rotations on dairy farms may contribute to climate change mitigation by facilitating carbon sequestration in soils. A long-term experiment in Denmark found that soil organic carbon (SOC) and soil total nitrogen (STN) increased with the proportion of GC (i.e., 2 and 4 years of GC in a six-year rotation) from 2006 to 2020. However, the incorporation of GC residues may potentially increase nitrous oxide (N2O) emissions due to the increased SOC and STN stocks. Yet, limited information exists regarding N2O emissions with different proportions of GC. We hypothesized that N2O emission will increase with more GC years in the rotation. This study aimed to quantify the emissions of N2O in two long-term crop rotations with different proportions of GC years (1/3 or 2/3), and all crops present each year. A one-year experiment is currently conducted including the rotation year preceding, and the year following GC cultivation where spring barley is cultivated, in both crop rotations (n=2, total: 8 plots). Emissions of N2O were quantified starting from April 2023 (day of year, DOY 111). Surface N2O fluxes were measured with the LI-7820 N2O/H2O trace gas analyzer connected to the 8200-01S Smart Chamber (LI-COR Biosciences, Lincoln, NE, USA). Linear mixed models were used to analyze N2O with crop rotation (1/3 or 2/3 GC) and rotation year (pre- or post-GC) as fixed effects and sampling date and block as random effects. Preliminary results showed elevated N2O fluxes (up to 443 ug N2O-N m-2 h-1) with a longer high-flux period in post-GC rotation years (DOY 111-151), than pre-GC years (DOY 111-139). The highest cumulative emission was 420 mg N2O-N m-2 in the post-GC year of DOY 320 in 1/3 GC. For pre-GC in 1/3 GC, pre-GC and post-GC in 2/3 GC, emissions were 249, 341 and 252 mg N2O-N m-2, respectively. For both N2O fluxes and cumulative emissions, the 1/3 GC rotation was significantly higher (p<0.01) than the 2/3 rotation. In addition, the N2O fluxes and cumulative emissions in the post-GC year were significantly (p<0.01) higher than the pre-GC year in the 1/3 GC crop rotation, while the years pre- and post-GC showed no difference in rotation with 2/3 GC. In contrast to our initial hypothesis, the preliminary results did not show higher N2O emissions with increased GC years. This currently suggests that the 2/3 GC inclusion in crop rotations has a greater potential for climate mitigation as compared to 1/3 GC. Further investigations will focus on the drivers of N2O emissions and the climate mitigation potential, considering both C sequestration in soil and N2O emissions in the long term.

How to cite: Kong, M., Petersen, S. O., Eriksen, J., and Dold, C.: Assessing Nitrous Oxide Emissions from Agricultural Soil: A Comparison of Two Grass-clover Proportions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1586, https://doi.org/10.5194/egusphere-egu24-1586, 2024.

16:28–16:38
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EGU24-7588
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ECS
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Virtual presentation
Yélognissè Agbohessou, Seydina Ba, Fabien Ferchaud, Joël Léonard, Sidy Sow, Fredéric Bouvery, Maxime Duthoit, Claire Delon, Rémi Vezy, Gatien N. Falconnier, Eric Mougin, Daouda Ngom, Simon Taugourdeau, and Olivier Roupsard

Agriculture contributes to climate changes through land use changes and greenhouse gas emissions. Models can provide crucial insights into the extent of this contribution; however, their effectiveness relies on proper evaluation within the application context. Moreover, crop models that can simulate greenhouse gas emissions have not been extensively tested for the semi-arid tropics. We calibrated and used the STICS soil-crop model to explore the skills of the model to reproduce observed variations in greenhouse gas emissions for a millet-groundnut rotation in an agro-silvo-pastoral parkland dominated by Faidherbia albida trees located in central Senegal. Model simulations were compared with observations of soil temperature, soil water content, N2O and CO2 emissions, aboveground and belowground biomass of millet and groundnut, collected between 2018 and 2022. CO2 emissions were simulated with a two-step approach. Initially, STICS simulated crop leaf area index and biomass (aboveground and belowground), and soil heterotrophic respiration. These variables were then integrated into an independent autotrophic respiration module, and summed with STICS simulated' heterotrophic respiration. In general, the STICS model tends to underestimate the observed minimum soil water content (wilting point) during the dry season and overestimate the observed soil water content after the wet season. However, the temporal dynamics of the soil temperature in the upper layer (0-30 cm) are generally well-represented by the model throughout the simulation period. Simulated N2O emissions were generally consistent in terms of magnitude compared to on-site measurements, although the model currently does not account for N2O absorption by the soil (i.e. negative fluxes). For instance, the simulated peak reached 0.041 kg N ha-1 d-1, while the observed peak was 0.048 kg N ha-1 d-1. The simulated average annual N2O emissions for the period 2018 to 2022 amounted to 0.368 kg N ha-1 yr-1. Simulated CO2 emissions were also comparable to on-site measurements (2021: EF = 0.63, BIAS = -0.75 kg C ha-1 d-1, and RMSE = 15.01 kg C ha-1 d-1; 2022: EF = 0.56, BIAS = -3.25 kg C ha-1 d-1, and RMSE = 5.01 kg C ha-1 d-1). These results indicate that the STICS model can be used to explore the impact of land use and crop management changes on greenhouse gas emissions in a tropical semi-arid context.

How to cite: Agbohessou, Y., Ba, S., Ferchaud, F., Léonard, J., Sow, S., Bouvery, F., Duthoit, M., Delon, C., Vezy, R., Falconnier, G. N., Mougin, E., Ngom, D., Taugourdeau, S., and Roupsard, O.: Modelling CO2 and N2O emissions from a tropical semi-arid parkland cultivated with groundnut and millet, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7588, https://doi.org/10.5194/egusphere-egu24-7588, 2024.

16:38–16:48
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EGU24-8547
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ECS
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On-site presentation
Jessica Chadwick, Iseult Lynch, and Sami Ullah

With the advent of synthetic nitrogen fertiliser, the proportion of reactive nitrogen (Nr) in terrestrial ecosystems has doubled. While this has enabled high crop productivity, it has also triggered mass environmental effects, with almost half of the applied fertiliser lost into air (in the form of N2O or NH3) as well as nutrient runoff and leaching of nitrates into water bodies. Nanomaterials present an opportunity to improve nutrient use efficiency of crops and minimise agricultural pollution via reducing losses. This study screened engineered nanomaterials, including zeolites and metal oxides, to assess their impact on greenhouse gas (CH4, N2O and CO2) emissions when co-applied with NPK (nitrogen, phosphorus and potassium) fertiliser to grow lettuce (Lactuca sativa). The findings show that there are highly differential emissions from soils with nanomaterial co-application with reduced fertiliser application rates. One of the zeolites used, ZSM-5-15, when co-applied with a reduced dose (50% of RB209 nutrient management guide recommendation) of NPK fertiliser, increased N2O emissions relative to reduced NPK fertiliser alone and negative controls. Another zeolite, BEA-19, had limited effect on either NH3 or N2O volatilization, but did reduce the concentration of ammonium in the leachate. Nitrate leaching gradually rose over the course of the 8-week experiment for full NPK fertiliser dose application, reduced NPK dose and negative control. This pattern was altered by BEA-19, triggering elevated nitrate leaching earlier in the experiment, peaking in week 1 compared to week 4 for other treatments. While nanomaterial treatment was able to increase lettuce biomass accumulation compared to full NPK and negative fertiliser treatments, understanding the impact of nanomaterials on N cycling has proven more complex. The mechanism for N loss from soils triggered by ZSM-5-15 application is unknown, potentially through impact on denitrifying enzymes. My work posits that the earlier release of nitrate from BEA-19 application is due to selective binding of the NPK to the nanomaterial surface. More data on nanomaterial endpoints is pending and may help elucidate the nature of this binding and nutrient release mechanisms.

How to cite: Chadwick, J., Lynch, I., and Ullah, S.: Greenhouse gas emissions under nanomaterial co-application with reduced fertiliser input, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8547, https://doi.org/10.5194/egusphere-egu24-8547, 2024.

16:48–16:58
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EGU24-9530
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On-site presentation
Maite Martínez-Eixarch, Sruthi Padinhariyil, Yolanda Lucas, Míriam Guivernau, Carles Alcaraz, Lluís Jornet, Julie Garnier, Adrien Fernández, Joan Noguerol, and Marc Viñas

Rice is a crucial crop for food security, but it is also a significant source of anthropogenic greenhouse gas emissions, particularly methane (CH4). Projected sea level rise caused by climate change will impact on rice yield through increased salinity. On the other hand, increased salinity potentially mitigates CH4 emissions by inhibiting methanogenesis mediated by the dominance of sulphate-reducing bacteria. To investigate this dual effect, we conducted a mesocosm experiment creating a water salinity gradient with four levels: 2 ppm (control), 4 ppm, 6 ppm and 35 ppm (seawater). CH4 emissions, abundance and gene expression of microbial populations and grain yield were assessed.

The experiment took place in year 2022 at IRTA facilities (Spain) using a variety of japonica rice (Oryza sativa L.). Rice was grown following the standard practices, notably permanent flooding, and crop residue incorporation into the soil after the harvest. CH4 emissions were weekly assessed throughout the rice growing season (May to September) and the post-harvest (October to December). Gas samples were collected using gas chambers and analysed through gas chromatography. Yield and aboveground biomass were measured at harvest. Thereafter, crop residues in each mesocosm, where present, were incorporated into the soil. Soil samples for microbial analyses were taken twice during post-harvest:  6 days before the harvest and 28 days after straw incorporation.  The microbial community diversity was assessed based on 16S/ITS-metataxonomy of total (DNA) and metabolically active (cDNA) bacteria, archaea, and fungi, as well as the quantification of total bacteria (16S rRNA gene), methanogenic archaea (mcrA gene ), and sulphate-reducing bacteria (aprA gene) by qPCR.  The activity of methanogenic archaea and sulphate reducing populations were assessed by quantifying gene transcripts of mcrA and aprA by RT-qPCR.

Rice grain yield decreased by 30% with increasing salinity from 2 ppm to 4 ppm, while there was no yield above 6 ppm. The biomass of straw produced and then added into the soil declined along the salinity gradient: 72.9 ± 12.4 g and 49.8 ± 6.1 g at 2 ppm and 4 ppm treatments, respectively, and zero in the remainder. The results confirmed that salinity significantly reduces CH4 emissions, but the sensitivity of this response differed between the growing and post-harvest seasons. During the growing season, CH4 declined with increasing salinity, ranging from 8.0 ± 1.7 to 0.05 ± 0.02 mg CH4 m-2 h-1. However, in the post-harvest, no CH4 emissions were detected at water salinities above 4 ppm, in contrast to 14.8 ± 0.75 mg CH4 m-2 h-1 found at 2 ppm. In regard to the microbial processes, the abundance of methanogenic archaea declined with increased salinity and the gene expression was highly inhibited at salinities larger than 6 ppm. By contrast, the abundance of sulphate-reducing bacteria was preserved over the salinity gradient while gene expression remained active, though slightly reduced from 6 ppm, probably due to the lower availability of organic carbon at the highest salinities.

Acknowledgments: The study has been carried out within the framework of the MIC-RICE project PID2019-111572RB-I00 funded by AEI/10.13039/501100011033

How to cite: Martínez-Eixarch, M., Padinhariyil, S., Lucas, Y., Guivernau, M., Alcaraz, C., Jornet, L., Garnier, J., Fernández, A., Noguerol, J., and Viñas, M.: Effect of a salinity gradient on methane emissions in paddy rice: a mesocosm experiment, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9530, https://doi.org/10.5194/egusphere-egu24-9530, 2024.

16:58–17:08
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EGU24-15750
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ECS
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On-site presentation
Chien Nguyen, Thi Bach Thuong Vo, Phuong Loan Bui, Van Trinh Mai, Tanh Nguyen, Klaus Butterbach-Bahl, Bjoern Ole Sander, Reiner Wassmann, Ralf Kiese, and David Kraus

The IPCC provides three distinct protocols (Tier 1-3) that can be used for reporting on greenhouse gas (GHG) emissions under the UNFCCC. While Tier 1 and 2 use relatively straightforward methods based on global and region-specific emission factors, Tier 3 is more complex and uses process models for emission estimation. Although Tier 3 is considered to have higher accuracy potential, its complexity requires expert knowledge and extensive input data, which is often not available, hindering widespread adoption.

This study critically evaluates all three Tier approaches for CH4 emissions from rice production in Vietnam, using the ecosystem process model LandscapeDNDC for the Tier 3 approach. As a first step, we evaluate all three approaches based on a comprehensive dataset covering 73 cropping seasons from 36 sites across Vietnam. On this basis, we show the extent to which Tier 3 performs better when considering commonly available information, and which information is most important to outperform simpler methods. As a second step, we present national CH4 emission inventories for each approach and show under which circumstances the approaches differ the most. We also present a web-based tool that improves the accessibility of Tier 3 applications for users who are not familiar with the application of a particular complex process model.

Our findings aim to provide valuable insights into the effectiveness of UNFCCC reporting approaches, particularly the under-researched Tier 3.

How to cite: Nguyen, C., Vo, T. B. T., Bui, P. L., Mai, V. T., Nguyen, T., Butterbach-Bahl, K., Sander, B. O., Wassmann, R., Kiese, R., and Kraus, D.: Assessing different IPCC Tier Approaches for estimating Methane Emissions in Vietnamese Rice Agriculture, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15750, https://doi.org/10.5194/egusphere-egu24-15750, 2024.

17:08–17:18
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EGU24-17763
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On-site presentation
Klaus Butterbach-Bahl and Ann-Britt Ann Britt Værge

In Denmark, the agricultural sector contributes almost 1/3 of total GHG emissions, second only to the energy sector. As significant GHG emission reductions have been achieved for the energy sector, there is increasing pressure on the agricultural sector to achieve GHG reductions of about 55-65% in the coming years.

While the current GHG emission inventory for the agricultural sector at national level in Denmark is based on a combination of Tier 1 and Tier 2 methodology following the standard IPCC methodology, the vision is to report national soil N2O emissions to the UNFCCC at either Tier 2 or Tier 3 level, the latter being the preferred level for the authorities as they plan to incentivize farmers to reduce emissions based on predictive yield and N2O emission models.

Against this background, the Danish SmartField initiative aims to establish an innovative field-scale platform for testing and validating solutions to reduce N2O emissions from agricultural fields. The data obtained will be used to further develop modeling tools for scaling, design and targeting of incentives to be included in regulatory frameworks to encourage adoption of knowledge and solutions by farmers and to ensure that these measures are accurately reflected in national inventories.

The core activities of SmartField are to establish: 1) a field measurement infrastructure to provide state-of-the-art benchmark datasets of N2O fluxes and other N loss and turnover pathways (NH3 volatilization and deposition, NOx fluxes, NO3 leaching, harvest N, soil N stock changes) for the most prominent field management practices in Denmark, including testing of classical and novel mitigation measures, 2) a data assimilation and modeling hub with a consolidated framework to provide evidence-based models for N2O emission quantification and to test N2O mitigation measures at large scale in scenario studies, and 3) a science-policy-practice interface (SPPI) to exchange knowledge and information and to build a smooth interaction with agricultural decision and policy models.

This will ensure that SmartField develops and delivers an improved methodology for accounting N2O emissions at field and farm scale, upon which policy incentives can be developed for farmers to adopt technologies and management measures with verified emission reductions.

SmartField is led by the Danish Technological Institute (DTI) in collaboration with Aarhus University (AU), the University of Copenhagen (UCPH), Colorado State University (CSU), SEGES Innovation (SEGES) and the Danish Ministry of Food, Agriculture and Fisheries (MFAF).

 

Note, that final funding decision for SmartField is pending approval

How to cite: Butterbach-Bahl, K. and Ann Britt Værge, A.-B.: SmartField – Accounting and mitigation of N2O emissions and N budgets of agricultural soils in Denmark, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17763, https://doi.org/10.5194/egusphere-egu24-17763, 2024.

17:18–17:28
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EGU24-18445
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ECS
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On-site presentation
Sharon Gubamwoyo, Gretchen Maria Gettel, Damaris Guranya Kisha, Sonja Leitner, Gabriele Weigelhofer, and Thomas Hein

Globally, agriculture is one of the main drivers of wetland loss, leading to reduced soil carbon (C) and changes in greenhouse gas (GHG) emissions. In recent decades, wetland loss in Africa appears to be faster than the global losses, at about 43% compared to 35% globally. Valley-bottom wetlands in African highland regions support the livelihoods of >65% of the people who live there, but the effect of agricultural conversion on soil C and GHG emissions is understudied. This study compares GHG emissions between 1 intact, 12 agricultural (converted), and 10 recovered valley-bottom wetlands in Taita Hills, Kenya. Using the static gas chamber method, CO2, CH4, and N2O emissions were measured monthly from April 2023 to date along with soil NO3-N, NH4-N, soil C, and soil moisture. The results indicate that CO2 emissions from the converted wetlands is similar to recovered wetlands (mean = 183 ± 11 SE mg CO2-C m-2 h-1 and mean = 174 ± 13 SE mg CO2-C m-2 h-1 respectively; p > 0.05). This is in contrast with both CH4 and N2O emissions, which showed strong differences (p<0.005). The average CH4 emission in agricultural versus intact wetlands was mean = 0.31 ± 9 SE mg CO2-C m-2 h-1 and mean = 10 ± 1 SE mg CO2-C m-2 h-1, respectively, and the N2O mean emission was mean = 41 ± 0.2 µg N m-2 h-1 vs. 9 ± 3 µg N m-2 h-1, respectively. Addition of organic and inorganic fertilizer to the agricultural wetlands showed an increase in NO3-N in the soil and a high correlation with N2O.  High soil moisture levels and organic matter in the intact wetlands was a major contributing factor for the high CH4 emissions while low soil moisture in the converted wetlands led to low CH4 emissions. The soil organic carbon in the recovered wetlands was higher (Mean = 11 ± 0.1 SE Kg C m-2) compared to the converted wetlands (Mean= 8 ± 0.2 SE Kg C m-2) indicating higher carbon storage in the recovered wetlands. Overall, recovered wetlands contribute more to Global Warming Potential GWP (0.84 CO2-equivalents), but these estimates do not take into account losses in soil C storage, which amount to 1043 Kg C m-2 year-1. On-going data analysis and field work will use seasonal variation and take into account historical losses in C storage to refine annual emission estimates.


Presentation preference: Oral, On-site
Billing address: Sharon Gubamwoyo
Gregor-Mendel-Straße 33/ DG34 
Institute of Hydrobiology
1180 Vienna, Austria

How to cite: Gubamwoyo, S., Gettel, G. M., Kisha, D. G., Leitner, S., Weigelhofer, G., and Hein, T.: Greenhouse gas emissions from valley-bottom wetlands in an agricultural tropical highland system, Taita Hills, East Africa, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18445, https://doi.org/10.5194/egusphere-egu24-18445, 2024.

17:28–17:38
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EGU24-20143
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ECS
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Virtual presentation
Priya Pariyar, Mary Harty, and Magdalena Necpalova

Managed grasslands influence global warming by the exchange of the greenhouse gases (GHG) like carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4). Application of animal waste, such as slurry, rich in inorganic nitrogen (N), may escalate soil processes and thus soil GHG emissions, particularly in organic systems that rely on input of animal manures without chemical inputs.

The objective of this study was to evaluate GHG mitigation potential of biological amendments that might be relevant to organic systems and their effects on soil N and N leaching over a 2-month period. To achieve this a plot-scale field experiment on a grassland site in Rosemount (Dublin, Ireland) was conducted over a period from May to July 2023. Closed static chamber technique was used to measure soil emissions of N2O, CH4 and CO2 with an increased sampling frequency after the slurry application. The dynamics of soil ammonium, nitrate and dissolved organic N were evaluated weekly in soil surface samples from 0-15 cm and in a 10-day interval in the leachate collected at a 50 cm depth. The grass yield was assessed twice during the course of the experiment. The plots were equally irrigated to stimulate soil processes during the dry periods. The treatments assigned to the plots in a randomised complete block design with 5 replicates included control (CON), cattle slurry (SLU) and slurry mixed with biochar (BIO; added at 2 kg/m2), neem oil high with slurry (NEEM H; added at 100% of N applied) and neem oil low with slurry (NEEM L; added at 20% of N applied). The slurry was applied at 50 kg N ha-1 to all plots apart from CON.

The application of neem oil at both levels of input consistently reduced soil N2O and CH4 daily emissions (p<0.001), while NEEM H at the same time increased soil CO2 daily emissions (p<0.001), compared to the SLU treatment. Biochar reduced soil CH4 daily emissions (p<0.001), but did not influence soil N2O and CO2 daily emissions relative to the SLU treatment.  

These results might be highly relevant for the climate-change policies relevant to organic farming systems and achievements of the national and international climate goals.

How to cite: Pariyar, P., Harty, M., and Necpalova, M.: Biological amendments reduce soil N2O and CH4 emissions from slurry application under field conditions., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20143, https://doi.org/10.5194/egusphere-egu24-20143, 2024.

17:38–17:48
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EGU24-10933
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ECS
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On-site presentation
Andrea Gozio, Matteo Longo, Miguel L. Cabrera, Roberto César Izaurralde, David E. Kissel, Barbara Lazzaro, Nicola Dal Ferro, and Francesco Morari

Agriculture is responsible for about 94% of UE ammonia (NH3) emissions, notably from livestock, manure management and soil fertilization. NH3 volatilization is a significant cause of reactive nitrogen (N) loss, leading to lower fertilizer efficiency as well as environmental and health concerns. Loss predictions can be estimated using process-based biogeochemical models, but many of them lack precise estimations of NH3 volatilization. In this work, we modified the Environmental Policy Integrated Climate (EPIC) model incorporating a mechanistic sub-model to simulate NH3 volatilization following the application of N fertilizers in agricultural fields. The newly added algorithm in EPIC functions on an hourly time step and describes the ammonium (NH4+) adsorption by clay and organic matter and estimates the partitioning of total ammoniacal N into NH3 and NH4+ based on the pH of the soil solution. The sub-model then determines the NH3 concentration in the gas phase using Henry’s law and estimates NH3 emission using a mass transfer coefficient that considers the resistance in the turbulent and laminar layers. Additionally, the sub-model uses the soil’s pH buffering capacity to recalculate pH following hydrogen ion consumption by urea hydrolysis and hydrogen ion release by NH3 volatilization. The sub-model further integrates a reduction factor for volatilization to account for the effects of soil layer depth and the depth of fertilizer application. The new EPIC sub-model was validated using datasets from Veneto, NE Italy, and Georgia, USA. In Italy, NH3 volatilization was measured in four experiments, testing cattle slurry, farmyard manure, and mixed silage maize and animal slurry digestate. Whereas in Georgia, NH3 volatilization was examined following surface application of urea and poultry manure to grasslands. The new sub-model improved NH3 loss prediction, yielding reasonable hourly NH3 fluxes and cumulative volatilization estimates. As a result, the EPIC model exhibited lower prediction errors for soil mineral N (e.g. NH4+and NO3-) dynamics. While the new sub-model marks a notable advancement in accurately modeling N cycling, additional enhancements should prioritize certain modeling aspects, including slurry infiltration rates, NH3 fluxes within the soil profile, and the mitigation effects resulting from urease inhibitor application.

How to cite: Gozio, A., Longo, M., Cabrera, M. L., Izaurralde, R. C., Kissel, D. E., Lazzaro, B., Dal Ferro, N., and Morari, F.: Optimizing Ammonia Volatilization Simulation in Agricultural Soils: Advancements of the EPIC Model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10933, https://doi.org/10.5194/egusphere-egu24-10933, 2024.

17:48–17:58
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EGU24-10183
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On-site presentation
Benjamin Loubet, Florence Lafouge, Sandy Bsaibes, Carole Bedos, Céline Decuq, Baptiste Esnault, Raluca Ciuraru, Julien Kammer, Raffaella Vuolo, and Valérie Gros

Pesticide usage has been expanding since the 1950s. Their use has been known to harm human and environmental health for decades. Pesticide volatilisation to the atmosphere is a known process which is however not well documented, especially for periods beyond a few days after pesticide application. This is partly due to the difficulty to measure gaseous pesticides concentration in the atmosphere continuously for long time periods. Indeed, current state-of-the-art measurements is made by thermo-desorption gaseous chromatography involving semi-manual sampling with cartridges.

In this study, we report first monthly outdoor online measurement of concentrations and volatilisation of one fungicide and two herbicides by proton transfer reaction, quadrupole injection, time of flight, mass spectrometry (PTR-QI-TOF-MS). The fungicide Chlorothalonil was measured over a wheat field in spring, while the herbicides Prosulfocarb and Pendimethalin were measured over a bare soil in autumn. Comparison with state-of-the-art TD-GC-MS and calibration by a home-made permeation system proved the PTRMS to be adapted for pesticides measurements.

Maximum measured concentrations ranged from 12 ppt for Chlorothalonil to 600 ppt Prosulfocarfb. Maximum daily volatilisation fluxes ranged from 35 ng m-2 s-1 for Chlorothalonil to 350 ng m-2 s-1 for Prosulfocarb. We found that volatilisation of Chlorothalonil lasted more than three weeks, leading to up to 50% of the applied quantity volatilised, a duration and an amount much larger that what has been reported before.

Volatilisation of pesticides may contribute much more significantly than expected to atmospheric burden, and be wet and dry deposited over larger areas. Further PTRMS pesticides measurements should be done to gain insight into pesticide transfer to the environment, and better characterize human exposure to these harmful compounds.

How to cite: Loubet, B., Lafouge, F., Bsaibes, S., Bedos, C., Decuq, C., Esnault, B., Ciuraru, R., Kammer, J., Vuolo, R., and Gros, V.: Online pesticide concentration and fluxes measurements over crops with a PTRMS shows unexpected volatilisation rates, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10183, https://doi.org/10.5194/egusphere-egu24-10183, 2024.

17:58–18:00

Posters on site: Thu, 18 Apr, 10:45–12:30 | Hall X1

Display time: Thu, 18 Apr 08:30–Thu, 18 Apr 12:30
Chairpersons: Christof Ammann, Alex Valach, Christian Brümmer
X1.45
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EGU24-7225
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ECS
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Deepakshi Babbar, Shilpi Kumari, and Srinidhi Balasubramanian

Food, feed, and fuel production are vital for human well-being. Yet current agricultural practices have resulted in extensive multi-media damages, primarily due to reactive nitrogen (Nr) emissions (NH3, N2O, NOx). Managing Nr sustainably to alleviate food and feed insecurity has been identified as a Grand Engineering Challenge. Systematically analysing source contributions, flows, and impacts of Nr is crucial for an agro-dominant country like India that faces the dual challenge of food and environmental security for 1.6 billion people by 2050. Here, we construct an Environmentally Extended Input-Output model for Nr in the Indian agriculture sector (cropland + livestock) for 2000–2020. Our findings indicate an increase in total N input to cropland from 23 Tg-N to 33 Tg-N (2000–2020), largely attributed to synthetic fertilizers (62%), biological N fixation (17%), atmospheric nitrogen deposition (11%), and livestock manure use (7%). Despite these increases, nitrogen use efficiency has only improved marginally (45% in 2000 to 57% in 2020). Nr losses to hyrosphere constitute 55%-60% of total N, with atmospheric emissions accounting for 40%-45% of total N. Key pollutants include nitrites/nitrates lost through runoff (40%), NH3 emissions (34%), and NO3 leakage to groundwater (20%). Noteworthy are NH3 emissions from fertilizer (55%) and manure (28%) application, and nitrogen deposition (12%).

Flows from the cropland sector serves as an input to the livestock sector, e.g., the production of grain and straw as feed to turn plant protein into animal protein, with efficiency varying from 4% to 10%. The type of animal and manure management systems and practices influences the N flow outputs from the livestock sector. Nitrogen within the remaining fraction (90–96%) is found in urine and dung, leading to potential nitrogen losses, i.e., 13.7TgN in the year 2020 due to the volatilization, leaching, and runoff as a result of application on cropland and manure management system of manure. Bovine animals have the largest share in manure N production, i.e., non-dairy cattle (37%), dairy (20%), and buffalo (26%), which constitute 83% of the total manure N production. Of the total produced manure (17Tg-N), 80% is produced in agriculture, and 20% is in pastoral areas. Of the agriculturally produced region, 30% undergo manure management system for treatment, i.e., 4TgN, while 70% are used for fuel combustion. Manure subjected to treatment is reintegrated into cropland at a rate of 52%, with approximately half being environmentally lost. Of this loss, 27% is attributed to atmospheric dissemination, comprising 22% as NH3 resulting from volatilization and 5% through direct emissions of N2O. Furthermore, 22% of the nitrogen is lost to the hydrosphere, distributed as 19% through runoff (0.8TgN) and 3% (0.1TgN) via NO3- leaching.   Opportunities to alleviate N losses and boost feed conversion efficiency involve refining animal feed composition and the herd's genetic potential. However, a challenge remains in upgrading manure management practices. Our study constraints national-scale inputs, accumulation, and flows of Nr in Indian agriculture to enable a holistic approach to co-develop agriculture and environmental policies while identifying levers to enable greener agricultural production practices.

How to cite: Babbar, D., Kumari, S., and Balasubramanian, S.: Environmental Footprint of Reactive Nitrogen in Indian Agricultural Sector: An Extended Input-Output Analysis  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7225, https://doi.org/10.5194/egusphere-egu24-7225, 2024.

X1.46
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EGU24-18441
|
Albrecht Neftel, Christoph Häni, Thomas Kupper, Alex Valach, and Sasha Hafner

Ammonia volatilization from animal slurry applied to fields is a major source of air pollution in Europe. The ALFAM2 model  was developed for estimating ammonia emission from such sources and is used in research, as well as  for inventory calculations. Until now, the focus has been on emissions up to 72 hours after application (ALFAM2 model version 1.2), as it was generally assumed that over 90% of total emissions from the applied nitrogen occur during this period. The recently updated ALFAM2 model (version 2.3) now includes emission data up to 168 h after application, which has led the model to indicate substantial emissions between 72 and 168 h leading to a significant increase (<40 %) in total emissions.

However, ammonia fluxes from field applied slurry beyond 72 h after application are small and difficult to quantify accurately. A reassessment of the model input data for this period is required to determine whether the measured fluxes can still be causally attributed to the applied slurry and whether they differ significantly from the detection limit. We have examined the values included in the ALFAM2 database with regard to these questions, which has revealed patterns that lead to potential biases of the ALFAM-2 model results.

How to cite: Neftel, A., Häni, C., Kupper, T., Valach, A., and Hafner, S.: Potential limitations of ammonia flux data beyond 72h after field application of slurries , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18441, https://doi.org/10.5194/egusphere-egu24-18441, 2024.

X1.47
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EGU24-19113
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ECS
|
Meshach Ojo Aderele, Jaber Rahimi, and Klaus Butterbach-bahl

Nitrogen pollution from livestock manure has emerged as an escalating global concern. Therefore, it is imperative to evaluate the cropping system that will facilitate the optimal utilization of livestock manure while minimizing the environmental impact. In the quest for sustainable agricultural practices, the incorporation of crop residues into soils and intercropping with catch crops, has been identified as promising strategies. Crop residue incorporation is a carbon farming practice that can have significant implications for both soil organic carbon (SOC) and nitrous oxide (N2O) emissions, while catch crops have been an essential tool for reducing nitrogen leaching.

This study uses the process-based biogeochemical model LandscapeDNDC to assess the environmental performance of different cropping systems in six representative Danish agricultural catchments (LOOPs). Generally, two fertilization strategies were distinguished: 1) fields receiving only a mixture of pig and cattle slurry (O-fields), and 2) fields (C-fields) receiving mineral fertilizer.

We tested eight scenarios of organic or conventional fertilized fields with or without crop residue incorporation and with or without catch crop (C/O ± CR ± CC)

The results revealed that organic fields demonstrated not only lower yield-scaled total emissions compared to conventional fields but also shows benefits in terms of net carbon balance. It therefore indicates that organic farming, especially when combined with crop residue and catch crop may lead to reduced nitrogen-related environmental impact while increasing yield.

How to cite: Aderele, M. O., Rahimi, J., and Butterbach-bahl, K.: Reducing Excess Nitrogen Through Sustainable Farming Systems in Danish Agricultural Catchments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19113, https://doi.org/10.5194/egusphere-egu24-19113, 2024.

X1.48
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EGU24-18307
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ECS
Sina Kukowski, Björn Kemmann, Pascal Wintjen, Jeremy Rüffer, Jens-Kristian Jüdt, Hannah Götze, Melanie Saul, Andreas Pacholski, Heinz Flessa, and Christian Brümmer

Primary sources of ammonia (NH3) emissions originate from agriculture, impacting the environment, climate, and human health, thereby concomitantly reducing fertilizer nitrogen use efficiency. Accurate measurements under field conditions are required to provide a basis process understanding and for recommendations to policymakers and farmers. However, uncertainties remain regarding the accuracy and reliability of different low-cost NH3 measurement methods and new application of the eddy covariance method for emissions from low-intensity sources, such as synthetic fertilizers.

In this study we focused on the quantification of NH3 concentrations and fluxes determined by a quantum cascade laser spectrometer (QCL) with passivated inlet line within an eddy covariance setup and the comparison to low-cost passive diffusion samplers (ALPHA sampler) used for emission estimations with the integrated horizontal flux (IHF) method. Measurements were carried out in Central Germany during the vegetation periods in 2021 - 2023 in a winter wheat crop field, which received three urea fertilizer applications (to a total of 170 kg N ha-1) per year. The atmospheric NH3 concentrations measured by the QCL and the ALPHA samplers were compared. Then, the cumulative losses of NH3 over the measurement periods (March - July) in the different years (2021 - 2023) were calculated and compared between the two approaches (QCL-eddy covariance and ALPHA-IHF).

The NH3 concentration measurements showed that the ALPHA samplers generally yielded lower concentration values compared to the time-integrated QCL values. While the relative mismatch decreased with higher concentrations (>20 ppb), significant deviations were observed in the lower concentration regime. When ALPHA concentrations were corrected for measurement height to precisely align with QCL sampling height, a systematic underestimation was found. Reasons for the differences are currently under investigation and may be explained by the vertical and horizontal sampler separation from the main eddy flux tower and possibly due to varying environmental conditions.  

First results of NH3 eddy covariance fluxes (kg N ha-1 period-1) showed clear diurnal courses and emission peaks around noon on the days after each urea application throughout all years. High-frequency losses using a co-spectral method in the process of eddy flux calculation were estimated to be in the range of 25 to 30 %.

The performance of both methods (ALPHA-IHF and QCL-eddy covariance) in estimating NH3 losses from field-scale fertilizer applications is discussed, along with the sensitivity of input concentrations on NH3 emission estimates.

Our study is a step towards better comparability and integration of different NH3 measurement techniques and is expected to provide useful tools for robust estimation of NH3 emission factors for synthetic fertilizer applications.

How to cite: Kukowski, S., Kemmann, B., Wintjen, P., Rüffer, J., Jüdt, J.-K., Götze, H., Saul, M., Pacholski, A., Flessa, H., and Brümmer, C.: Measuring ammonia losses from winter wheat with eddy covariance: a comparative analysis with the integrated horizontal flux method, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18307, https://doi.org/10.5194/egusphere-egu24-18307, 2024.

X1.49
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EGU24-16270
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ECS
Ferdinand Hartmann, Heide Spiegel, Eugenio Diaz-Pines, and Rebecca Hood-Nowotny

Agriculture and other land use practices are major contributors to greenhouse gas emissions. To meet the needs of an increasing global food demand while mitigating climate change, sustainable agricultural practices are necessary. Biochar seems to be a promising tool to support this transition to sustainability in agriculture. The application of nitrogen fertilizers increases N2O emissions and NH3 volatilisation. Nitrous oxide (N2O) is a highly potent greenhouse gas and ammonia (NH3) can re-react with soil and forms N2O or can lead to other environmental issues in the surrounding. Besides its carbon sequestration potential, it is known that biochar can positively influence soil properties like water holding capacity, nutrient leaching and mitigation of nitrous oxide emissions and ammonia volatilisation. However, these effects depend on pedoclimatic conditions, the properties of the applied biochar, and other agricultural practises. Therefore, it is necessary to expand the knowledge of these effects, especially under field conditions, to generate valid estimates on biochar’s mitigation potential for N2O and NH3 emissions. A good and extensive data basis is essential for recommendations and a large-scale application in agriculture. In a two-year field experiment in Grabenegg (Lower Austria) we cultivated silage maize (Zea mays) in 2022 and spring wheat (Triticum aestivum) in 2023 with different organic (external organic matter, EOM) and inorganic (NPK) fertilisers. For the biochar treatments we applied 7 t/ha hardwood biochar additionally. The original soil was loamy, low in organic carbon and slightly acidic. We found substantial reductions with 36% (NPK) and 53% (compost) for N2O and 56% (NPK) and 40% (compost) for NH3 emissions. There are several factors discussed in literature how biochar mitigates N2O and NH3 emissions. We suggest that the immobilisation effect of biochar on NH4+ and NO3- (which was observed in the soil), and possibly an increased dinitrogen monoxide reductase activity are responsible for this reduction. Our data support that biochar can be a suitable amendment for highly productive agroecosystems where high amounts of fertiliser are needed and often applied at one timepoint. Still, further investigations on the long-term effect on emission mitigation of biochar and the mechanisms behind are necessary.

How to cite: Hartmann, F., Spiegel, H., Diaz-Pines, E., and Hood-Nowotny, R.: Impacts of biochar on nitrous oxide emissions and ammonia volatilisation in wheat and maize cropping systems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16270, https://doi.org/10.5194/egusphere-egu24-16270, 2024.

X1.50
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EGU24-16666
Balázs Grosz, Jörg Michael Greef, Linda Tendler, Mahboube Jarrah, and Rene Dechow

The positive and negative effects of animal manure application to agricultural soils on soil inorganic nitrogen content, crop yield, ammonia (NH3), and nitrous oxide (N2O) emissions are well known and integrated into biogeochemical models. However, it is unclear if the effects of using digestate from biogas plants as fertilizer can be described by biogeochemical process models too. Since in Germany, the number of biogas plants increased drastically in the last two decades, there is a need for an evaluation and calibration of biogeochemical models for the application of digestate on arable land. For this purpose, we used data from a field experiment consisting of a control without fertilization, 3 treatments with mineral fertilizer, and 3 treatments with biogas digestate application (each with 60%, 80%, and 100% of maximum required N) on two cereal/maize crop rotations. Digestate was applied using trailing hoses. Results from experiments are used to calibrate and improve the biogeochemical model DNDCv.Can. Starting from a simplified description of O2 transport, a new sub-module quantifies O2 concentration by coupling decomposition with a 1-dimensional diffusion approach. Since the size of the anaerobic balloon calculated by the model influences many processes occurring in the soil, such as nitrification and denitrification, we hypothesize that a more realistic description of O2 concentration, together with a model calibration addressing the decomposition kinetics of digestate, will lead to a more precise process description and, thus, to a better estimation of N2O and, indirectly, NH3 gas fluxes, and to more reliable estimation of NO3- and NH4+ contents in the topsoil.

How to cite: Grosz, B., Greef, J. M., Tendler, L., Jarrah, M., and Dechow, R.: Modeling N2O, NH3 fluxes, and Nmin concentrations in agricultural soils treated with biogas digestate using a modified DNDC model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16666, https://doi.org/10.5194/egusphere-egu24-16666, 2024.

X1.51
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EGU24-3488
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ECS
Qiaoyan Li, Klaus Steenberg Larsen, and Christiana Amalie Dietzen

The application of ground silicate minerals to agricultural ecosystems has recently gained popularity as a mechanism for CO2 removal via enhanced mineral weathering that also has the potential to provide valuable co-benefits, including improved crop yields and reduced emissions of other greenhouse gasses. In Greenland, finely grained glacial rock flour (GRF) is naturally generated in vast amounts by glacier movement causing bedrock erosion and deposition. The natural production of GRF means that less energy is needed for grinding the rock material prior to field application. To quantify the influence of GRF on ecosystem carbon balance and greenhouse gas emissions, we applied 10 to 50 t GRF ha-1 yr-1 to an agricultural field in Denmark in a gradient setup with 5 levels plus combinations with fertilizers. Preliminary results of the CO2 fluxes measured by a combination of automated and manual chamber measurements, show that gross primary productivity (GPP, carbon uptake) and ecosystem respiration (Reco, carbon release) both increased gradually with the increased addition of GRF leading to a slightly increased net ecosystem uptake of CO2. In contrast, CH4 and N2O emissions showed a negative response trend with the increasing addition of GRF. The annual quantifications of ecosystem carbon balance and greenhouse gas emissions need further observations including effects during the non-growing season to be finalized. However, our initial results support the hypothesis that silicate mineral amendment overall may enhance CO2 removal in agricultural settings and reduce greenhouse gas emissions, and therefore may be a useful tool for improving the capacity of farmlands to serve as a greenhouse gas sink.

How to cite: Li, Q., Larsen, K. S., and Dietzen, C. A.: Positive mitigation effects of glacial rock flour (GRF) addition on ecosystem CO2, CH4 and N2O fluxes – first results from a gradient experiment, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3488, https://doi.org/10.5194/egusphere-egu24-3488, 2024.

X1.52
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EGU24-11524
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ECS
Susanne Wiesner, Shabda Gajbhiye, Shourya Mehta, Paul Stoy, and Alison Duff

Decades of intensive agricultural production, consisting of monoculture crops like corn (Zea mays), has led to a drastic decline in soil health, indicated by a reduction in soil carbon, nutrient holding and water holding capacity. Shifting management from monoculture crops to perennial crops could improve these soil characteristics and boost the resilience of agricultural systems to climate change. Furthermore, dairy livestock production systems are major greenhouse gas (GHG) emitters. GHGs from crop-livestock systems originate from enteric fermentation, manure storage, soils, and farm energy use. Nevertheless, US dairy herd sizes have not changed significantly in recent decades, suggesting that annual enteric fermentation emissions remained constant, while manure and soil emissions (i.e., CO2, N2O, CH4) increased from the intensive management, including tillage and the application of agricultural chemicals. However, soil emissions such as CO2 efflux (efflux) also consists of natural biogenic emissions from plant and microbial activity. Hence, an efflux may indicate greater soil health, suggesting root activity and high soil microbial abundance. Similarly, less variability in soil moisture and temperature could indicate high compaction and inferior soil structure. Understanding the multiple responses of soils to agricultural management is critical for developing strategies to improve soil health.

Here we established a nested treatment experiment with four block replications and three replicated plots per block (30 by 30 feet) using six different cropping systems (corn, corn with cover crop, corn intercropped alfalfa (Medicago sativa), alfalfa, intermediate wheatgrass (IWG, Thinopyrum intermedium), and a five species mixture of pasture grasses and forbs), to understand the system tradeoffs among soil health, forage quality and milk production in a dairy agricultural system. To quantify changes in soil health, structure, and soil GHG emissions, we planted corn on all plots in year 1 (2020) before planting other treatments in year 2 (2021). We collected data on soil nutrients and carbon content, soil microbial abundance and diversity, soil CO2 efflux, soil moisture and temperature, as well as forage samples and multispectral drone flights to assess forage quality.

Corn plots (monocultures and intercropped) had lower variability in environmental characteristics like soil moisture and temperature, while their magnitudes were elevated, indicating a more compacted and less aerated soil compared to plots with greater root density and lower bulk density (i.e., pasture plots). Similarly, corn plots respired significantly less CO2, both in years 1 and 2, compared to perennial crop plots, conforming with soil microbial data, which indicated lower microbial diversity in corn plots compared to pasture plots. While corn biomass was greater at the time of harvest compared to other crops, pasture and alfalfa plots accumulated half of the corn biomass throughout three harvest cycles and showed to have lower variability in yield, while also having higher nutritious value compared to corn silage, with implications for milk quality. Our findings suggest that efforts to make dairy operations more resilient to climate change and weather extremes should focus on more variables than just GHG emissions and soil carbon storage, to sustain agricultural production, human nutrition, and biogenic nutrient recycling into the future.

How to cite: Wiesner, S., Gajbhiye, S., Mehta, S., Stoy, P., and Duff, A.: Understanding soil health across greenhouse gas emissions and soil characteristics, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11524, https://doi.org/10.5194/egusphere-egu24-11524, 2024.

X1.53
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EGU24-386
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ECS
Does a soil drying-rewetting cycle decrease the effectiveness of nitrification inhibitors?
(withdrawn)
Pablo Ribeiro and Karl Mühling
X1.54
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EGU24-5275
Narasinha Shurpali, Olli Peltola, Tulasi Thentu, and Perttu Virkajärvi

Grasslands are a key component of boreal agriculture and can play a significant role in soil carbon sequestration and mitigation. Grasslands have the potential to store substantial amounts of carbon in their roots and soil, making them important for soil carbon sequestration. Finland, located in the boreal climate zone, is known for its milk production with one of the highest per cow milk yields in Europe. Milk production in Finland relies heavily on grassland management. The growing season is short and varies from 105 days in the north to 185 days in the south. Finnish grasslands are managed on two types of soils: mineral soils and organic soils. Mineral soils are typically well-drained and have a low organic matter content, whereas organic soils are characterized by high organic matter content and high-water retention capacity. Therefore, we have initiated a long-term GHG monitoring framework for a sustainable grassland management and agriculture at the Natural Resources Institute Finland (Luke) across several agricultural research sites in Finland. The results presented in this study will shed light on the variability of GHG-fluxes from grasslands on different soil types and on the key drivers of the temporal and site variability of GHG-fluxes in a comparative way.

How to cite: Shurpali, N., Peltola, O., Thentu, T., and Virkajärvi, P.: Impact of management and boreal climate on GHG exchange from Finnish grasslands on mineral and peat soils, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5275, https://doi.org/10.5194/egusphere-egu24-5275, 2024.

X1.55
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EGU24-10130
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ECS
Elysia Lewis, Matteo Longo, Sebastiano Rocco, Nicola Dal Ferro, Miguel Cabrera, Barbara Lazzaro, and Francesco Morari

Soil structure plays a crucial role in determining greenhouse gas (GHG) emissions from agricultural activities. Changes in soil structure, such as compaction, can alter the factors that govern GHG fluxes, leading to an increased potential for emissions. The extent to which soil compaction explains GHG emissions is still under investigation. To address this knowledge gap, a two-year experiment was conducted in Northeast Italy to examine the influence of soil compaction on GHG emissions. The experimental site comprised of 20 lysimeters representing five different cultivation systems, each with four replicates: bare soil (BS), conventional (CV), conventional + with cover crop (CC), conservation with shallow compaction (0-25 cm, CA1), and conservation with deep soil compaction (25-45 cm, CA2). Maize was cultivated as the main crop in 2022, followed by grain sorghum in 2023, with solid digestate (300 kg N ha-1) originated from mixed agricultural waste used for fertilization. Winter wheat served as a cover crop where necessary. Continuous automatic measurements of CO2, N2O, and CH4 emissions were collected using a non-steady state through-flow chamber system and an FTIR gas analyzer, enabling the capture of up to seven fluxes per day for each replicate. Additionally, water-filled pore space (WFPS) and soil temperature were continuously monitored in the 0-30 cm soil profile using Time Domain Reflectometry (TDR) sensors and thermocouples. Cumulative CO2 reached its peak under CV, followed by CC. Notably, observable N2O emissions were predominantly detected in the two weeks following fertilization with peaks reaching 0.8 kg N-N2O ha-1d-1 under CC, while CA1 and CA2 exhibited lower emissions. Conversely, CH4 emissions were negligible, and the soil primarily acted as a sink. The study provides crucial insights for sustainable agriculture by highlighting the impact of soil compaction on GHG.

How to cite: Lewis, E., Longo, M., Rocco, S., Dal Ferro, N., Cabrera, M., Lazzaro, B., and Morari, F.: Understanding the influence of soil compaction on greenhouse gas emissions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10130, https://doi.org/10.5194/egusphere-egu24-10130, 2024.

X1.56
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EGU24-19925
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ECS
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Csilla Gombi, Anna Szabó, Csaba Király, Vineet Srivastava, László Horváth, Edit Mikó, Gábor Szabó, and Zoltán Bozóki

The efficiency of fertilisers used worldwide is around 50%. It is a global environmental and economic problem, and intensive research is being conducted to find a solution. Nitrous oxide (N2O) is one of the nitrogen compounds released from fertilised soils. N2O is also emitted during the storage, treatment, and application of animal manure, in addition to fertilisers.

To reduce emissions, gas concentration and emission monitoring is important for accurate estimation of agricultural losses and to establish regulations for mitigation purposes. Laser spectroscopy-based methods provide in-situ, highly selective measurements with minimal maintenance, therefore they are promising techniques for monitoring N2O. A photoacoustic system based on a quantum cascade laser emitting around 7.72 μm was developed for N2O concentration measurement. Selectivity of the system was tested for water vapour (H2O), carbon dioxide (CO2) and methane (CH4). No cross sensitivity was found for H2O and CO2, nevertheless for CH4 it is not negligible, therefore a two-wavelength method is applied to correct for CH4. The system has a minimum detectable concentration of 8.5 ppb with an averaging time of 10 seconds. The system was calibrated from 0.05 ppm to 10 ppm, the response was found to be highly linear over the calibrated range (R2 = 0.9989).

A feasibility study was performed in a naturally ventilated free-stall dairy barn. Measurements were taken at a total of six measurement points, two of which were outside the barn and four inside the barn where spatial and temporal variations of N2O concentration were measured. Measurements taken outside the barn were considered to be close to the background (333 ppb). There, the measured concentration was 388 ppb ± 11 ppb. The measured mean N2O concentration inside the barn was 499 ppb ± 191 ppb during a three-hour period, and it varied between the near background concentration and 1 ppm. The system has a signal stability allowing for field applications; however, further tests are required to prove its applicability for quantifying biosphere-atmosphere exchanges of N2O. In the future our measuring system will be applicable to monitor N2O emission flux above crop fields and at livestock farms as well.

How to cite: Gombi, C., Szabó, A., Király, C., Srivastava, V., Horváth, L., Mikó, E., Szabó, G., and Bozóki, Z.: Photoacoustic spectroscopy based nitrous oxide measurement for field applications, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19925, https://doi.org/10.5194/egusphere-egu24-19925, 2024.

X1.57
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EGU24-17542
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ECS
Xiao Bai, Lars Andreassen, Gülnur Dogan, and Klaus Butterbach-Bahl

Global urbanization has significantly affected land use, with former agricultural or forested land being used for human settlements and urban green spaces. How this urbanization may have affected the spatial and temporal patterns of soil greenhouse gas (GHG) fluxes, especially those of nitrous oxide (N2O), remains largely unexplored, although a recent study indicated that urbanization accelerates GHG fluxes from soils.

In this study, we investigated soil GHG fluxes at Aarhus University Park (AU Park), a public park located in a hilly landscape with different use intensities. Soil GHG fluxes were measured 2-3 times per week over a period of 7 months using a fast chamber approach at about 55 sampling points with different management, vegetation, and landscape position (uphill, slope, foothill, ponds). Specifically, we focused on the identification of GHG flux hot and cold spots, and thereby investigated the temporal persistence of such spatial emission patterns.

Our results show that GHG fluxes were highly variable over the observation period, but that major GHG flux hotspots, such as those near a pond, were hotspots at all observation times. In addition, we were able to relate the spatio-temporal variations in soil GHG fluxes to landscape parameters such as slope and exposition, and to soil parameters such as soil organic carbon concentration, pH, and texture.

Our measurements show that there are significant spatio-temporal variations in GHG fluxes in urban parks and that these variations are strongly influenced by environmental and landscape parameters. This observation may allow a better scaling of GHG fluxes of urban green spaces and thus a better assessment of how urbanization changes landscape fluxes.

How to cite: Bai, X., Andreassen, L., Dogan, G., and Butterbach-Bahl, K.: Spatial and temporal variability of soil GHG fluxes of urban greens, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17542, https://doi.org/10.5194/egusphere-egu24-17542, 2024.

Posters virtual: Thu, 18 Apr, 14:00–15:45 | vHall X1

Display time: Thu, 18 Apr 08:30–Thu, 18 Apr 18:00
Chairpersons: Christian Brümmer, Alex Valach, Christof Ammann
vX1.4
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EGU24-7554
Yang Yuming

Global warming, mainly caused by greenhouse gas (GHG) emissions, is one of the major concerns of the current society. Accurate estimation of GHG emissions in various fields can help governments and international organizations to formulate emission reduction strategies.The main objectives of this study were to estimate CH4 and N2O emissions from rice-wheat crop fields using IPCC2006 Tier2 approach and DNDC model, and to compare the performance of the two methods; and to evaluate the accuracy of GHG emissions of the DNDC model with rotational and non-rotational simulation scenarios. In this study, we conducted a rice-wheat rotational field experiment from 2015 to 2018 to determine CH4 and N2O fluxes periodically using static chamber-gas chromatography measurement and analysis system. On this basis, combined with field management and meteorological data, we simulated GHG emissions from rotational and non-rotational crop scenarios using the IPCC2006 Tier2 approach and the DNDC model. The results show that (1) the DNDC model can simulate the time series of paddy CH4 and N2O emission fluxes and winter wheat N2O emission fluxes with estimation errors of -4.8%, -11.6%, and -10.8%, respectively, and the modeling accuracy is better than that of the IPCC2006 Tier2 approach; (2) the accuracy of the DNDC model for simulating the GWP under the rotational cropping scenarios was higher than that of the IPCC2006 Tier2 approach, the relative errors of GWP simulation in the DNDC model were -5.9% and -21.7% for rice and wheat fields, respectively; (3) the relative errors of winter wheat cumulative CH4 emissions in the rotational cropping scenario in the DNDC model were higher than those in the non-rotational cropping scenario, and the relative errors of cumulative emissions of other GHGs in the rotational cropping scenario were lower than those in the non-rotational cropping scenario.This study provides some references for estimating regional agricultural GHG emissions and formulating emission reduction targets and policies.

Keywords: Rice-wheat rotation; DNDC; IPCC2006 Tier2; Greenhouse gases

How to cite: Yuming, Y.: Study on the difference of rice-wheat rotation system greenhouse gas estimation by different simulation methods, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7554, https://doi.org/10.5194/egusphere-egu24-7554, 2024.

vX1.5
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EGU24-6572
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ECS
Folahanmi Adeyemi

Global climate change is forcing different sectors including agriculture to come up with mitigation strategies. Nitrous oxide is the most potent greenhouse gas that contributes to global warming and is mainly produced from agricultural soil management. Two mitigation strategies to potentially reduce nitrous oxide emissions while maintaining cash crop yields are (i) shifting from conventional tillage to no-till and (ii) incorporating winter rye (Secale cereale L.) into corn (Zea mays L.)-soybean (Glycine max L.) rotation as a typical production system in the Midwest, USA. We harnessed a long-term trial to evaluate soil N dynamics, moisture and temperature, soybean production, and nitrous oxide emissions during 2020 and 2022 growing seasons. Treatments were two tillage factors (no-till and conventional chisel-disk) and two cover crops (winter rye and a no-cover crop control) arranged in factorial design with three replications. Results indicated that in 2020, no-till-no-cover crop had less nitrous oxide fluxes than the winter rye treatments, however it had higher N2O-N losses than 2022.  A combination of winter rye-no-till provided similar soybean morphology, shoot biomass and grain yield compared to a tillage-based system with no cover crop but promoted soybean root biomass leading to greater carbon inputs. These results indicate the tradeoffs in benefits of winter rye in soybean cropping systems.

How to cite: Adeyemi, F.: Soybean growth and nitrous oxide emissions in response to tillage and crop rotation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6572, https://doi.org/10.5194/egusphere-egu24-6572, 2024.