SSS9.13 | Trade-offs between soil carbon sequestration, greenhouse gas fluxes and N and P losses: implications for agriculture management

SSS9.13

Trade-offs between soil carbon sequestration, greenhouse gas fluxes and N and P losses: implications for agriculture management 

Measures for increasing soil organic carbon in agricultural soils are becoming increasingly popular as part of the global efforts to mitigate climate change. A large range of management strategies (e.g. minimizing soil disturbance, diversification of crop rotations, use of cover crops, incorporation of crop residues, addition of organic amendments, rewetting organic soils) are investigated in a range of socio-ecological contexts to evaluate their role of sequestering carbon in the soil.
Increasing organic carbon content in soils has several co-benefits, beyond climate change mitigation, including improvement of soil health, fertility and water holding capacity. On the other hand, agricultural strategies aimed at increasing carbon sequestration may affect other element cycles, with implications for greenhouse gas fluxes (N2O and CH4) fluxes, and losses of C, N and P to ground- and surface waters. Thus, the overall effect of these management practices needs to be evaluated to appropriately quantify their environmental impact.
In this session, we welcome contributions that give insights into the effects of agricultural management practices, aimed at improving carbon sequestration, on the greenhouse gas balance and on element losses to ground and surface waters. We welcome experimental, modelling or synthesis approaches, but a special focus will be given to studies trying to understand the causes and mechanisms of the observed trade-offs and/or synergies.

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Convener: Eugenio Diaz Pines | Co-conveners: Tuula Larmola, Cristina Aponte, Mart Ros, Ana Meijide
Orals
| Mon, 24 Apr, 16:15–18:00 (CEST)
 
Room -2.20
Posters on site
| Attendance Mon, 24 Apr, 10:45–12:30 (CEST)
 
Hall X3
Posters virtual
| Attendance Mon, 24 Apr, 10:45–12:30 (CEST)
 
vHall SSS
Orals |
Mon, 16:15
Posters on site |
Mon, 10:45
Posters virtual
Mon, 10:45

Orals: Mon, 24 Apr | Room -2.20

The oral presentations are given in a hybrid format supported by a Zoom meeting featuring on-site and virtual presentations. The button to access the Zoom meeting appears just before the time block starts.
Chairpersons: Eugenio Diaz Pines, Cristina Aponte, Tuula Larmola
16:15–16:20
5-minute convener introduction
16:20–16:40
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EGU23-2587
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solicited
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On-site presentation
A meta-analysis of field experiments on the effect of organic matter inputs on N2O emissions in European arable land 
Elena Valkama, Domna Tzemi, Ulises Ramon Esparza Robles, Adam O'Toole, and Alina Syp

The focus of previous research regarding the effects of applying organic matter inputs on carbon sequestration has been mostly restricted to a simple quantification of soil organic carbon stock or CO2 balance. However, all a more comprehensive assessment of net carbon balance should also consider non-CO2 GHG sources and sinks across the soil-plant system. The objective of this study is to synthesize results from field experiments, which explore the effects of adding different organic matter inputs to soil on N2O emissions in Europe.

A comprehensive literature search was conducted using keywords in Web of Science, Agricola, Scopus, ScienceDirect, Google Scholar, and in the reference list of published reviews and meta-analyses. We included European experiments with diverse arable crops cultivated in monoculture or in crop rotations on mineral soils. Cumulative N2O emissions were monitored in the fields that received either solely organic matter inputs (crop residues, green manure, livestock manure, slurry, digestate, compost, biochar or sludge) or in combination with inorganic fertilization, and inorganic fertilization served as a control. Laboratory, greenhouse studies, or field studies solely on organic soils were excluded from the database, as well as studies on permanent crops, pasture, rice fields, forest and semi-natural areas and wetlands.  

The entire database consists of 51 peer-reviewed scientific articles published between 1993 and 2022, and three unpublished items. Nitrous oxide emissions were measured at each site over a period of one month to three years in about 50 sites, in 16 European countries covering all European climate zones, from Alpine North to Mediterranean South. Annual rainfall and average annual temperature varied between 250 mm and 1300 mm, and between 4.5 ⸰C and 19.6 ⸰C, respectively. The impact of organic matter input in terms of quantity, nature, as well as quality was captured by C/N ratio (1 - 390) and amount of N (20 - 420 kg ha-1).  The list of potential moderators consists of soil physical and chemical properties, such as the percentage of soil organic C, clay, silt, sand, soil texture, C/N ratio and pH for each site, and agricultural management practices, such as type and the amount of inorganic fertilization, tillage system, crop residue management and irrigation type.

The mean values of cumulative N2O emissions for a duration, standard deviations, and sample sizes (equal to the number of replicates) for organic matter inputs and inorganic fertilization were extracted from tables and figures in articles. To perform a meta-analysis, logarithm response ratio as an index of effect size will be calculated for each study, which will then be summarized across the studies by using weighing procedure. The impact of pedo-climatic characteristics, agricultural management practices, the nature and quality of organic matter inputs on N2O emissions will be studied. Findings of the current meta-analysis will provide a robust conclusion on which type of organic matter inputs under which pedo-climatic conditions and management practices emit negligible or significant amount of N2O compared to inorganic fertilizers.   

How to cite: Valkama, E., Tzemi, D., Esparza Robles, U. R., O'Toole, A., and Syp, A.: A meta-analysis of field experiments on the effect of organic matter inputs on N2O emissions in European arable land, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2587, https://doi.org/10.5194/egusphere-egu23-2587, 2023.

16:40–16:50
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EGU23-12863
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On-site presentation
Net ecosystem carbon balance, emissions of methane and nitrous oxide and water quality in the first four years of rewetting a cultivated peat soil site for paludiculture 
Kristiina Lång, Hanna Kekkonen, Henri Honkanen, Jaakko Heikkinen, Sanna Saarnio, and Tuula Larmola

Cultivated peatlands are a major source of greenhouse gas (GHG) emissions and water pollution in northern Europe, and their future management is a key issue on the path to carbon neutral societies. Conventional cultivation requires drainage, and above the drainage depth all peat is prone to decomposition with the implication that these soils have the highest emission rates per area compared to any other land use. Paludiculture is a management option in which wet-tolerant crops are produced with raised ground water levels. It is thus a GHG mitigation method that allows for slowing down peat decomposition in drained peatlands while still maintaining agricultural income for the landowner. There are tradeoffs to consider when implementing paludiculture: 1) methane emissions rise with the switch of aerobic to anaerobic decomposition, 2) slowing down decomposition reduces nutrient mineralisation from the peat and compromises productivity and 3) harvesting reduces the potential to sequester carbon to the ecosystem compared to natural wetlands. 

We experimented paludiculture at a highly degraded peat site in southern Finland with plots of willow, forage, and mixed vegetation (set-aside). We recorded the yields, emissions of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) and auxiliary environmental data for four years, as well as nutrient content of the soil water for two years. We will present the results of these measurements, including estimates on the net ecosystem carbon balance of each crop based on empiric models.  

Raising the ground water level to the desired depth (-20 cm) turned out to be challenging. The mean annual ground water table levels during the four study years were about 80, 40, 40 and 30 cm (the measurements of the last year are still ongoing). The preliminary results suggest that even a slight raise of the ground water level was able to slow down CO2 emissions from soil respiration, while an increase in CH4 emission partly counteracted this benefit especially when the ground water level was above 30 cm. Nitrous oxide emissions were extremely high after the initial disturbance of the site but remained at a relatively low level after that. The results will be compared to an adjacent site with an annual crop, and paludiculture as a mitigation measure discussed.  

How to cite: Lång, K., Kekkonen, H., Honkanen, H., Heikkinen, J., Saarnio, S., and Larmola, T.: Net ecosystem carbon balance, emissions of methane and nitrous oxide and water quality in the first four years of rewetting a cultivated peat soil site for paludiculture , EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12863, https://doi.org/10.5194/egusphere-egu23-12863, 2023.

16:50–17:00
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EGU23-9598
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ECS
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On-site presentation
Co-application of organic amendments and urea-N enhanced CO2 and N2O emissions from a sandy soil; insights of soil N transformations and organic amendments quality. 
Georgios Giannopoulos, Elpida Pasvadoglou, George Kourtidis, Lars Elsgaard, George Zanakis, and Ioannis Anastopoulos

Under the framework of Circular Economy, EU Green Deal and UN Sustainable Development Goals the use of organic amendments is highly promoted as a cost-efficient solution to improve soil quality and agrosystem sustainability. Nonetheless, their agronomic use comes with an uncertainty of their potential to release ample plant-available N, and to emit soil greenhouse gasses.

We investigated short-term (90 d) soil N dynamics of a sandy soil mesocosms receiving four organic amendments (50 t/ha) (i) cow manure compost (CMC), (ii) food waste compost (FWC), (iii) used digestate substrate (UDS) and (iv) municipal sewage sludge (MSS), without and with N fertilization (200 kg/ha; urea-N). An unamended soil mesocosm was included as control. During the incubation soil NO3-, NH4+, N2O and CO2 were regularly monitored. At the end of the incubation potential N mineralization (AMN), total Kjeldahl N, organic C, and trace-metals were determined.

During the incubation, organic amendments increased ~6x soil NO3- availability (AUC) than C, however soils receiving MSS had similar AUC NO3- to the fertilized soils (~13x). Only MSS increased ~5x available soil NH4+ (AUC) relative to unamended soil. Co-application of urea and organic amendments increased AUC NO3- and AUC NH4+ ~5x, relative to the unamended soil. Organic amendments increased cum. N2O emission by 10, 20, 1% and 13x relative to the control, and additional 20% increase when urea was co-applied for CMC, FWC, UDS and MSS, respectively. Similarly, organic amendments increased cum. CO2 emission by 20, 40, 140, and 1% relative to the control, and additional 10% increase when urea was co-applied for CMC, FWC, UDS and MSS, respectively.

At the end, total N increased by 37, 23, 80 and 20% relative to the unamended soil, and an additional 20% when urea was co-applied for CMC, FWC, UDS and MSS, respectively. Org. C increased by 30, 20, 4 and 50%, and an additional 7% when urea was co-applied for CMC, FWC, UDS and MSS, respectively. AMN increased 2, 50 and 220% and an additional 20% when urea was co-applied for CMC, FWC and MSS, respectively, whereas no change was observed for soil receiving UDS relative to the control. Treatments receiving MSS without and with N had relatively higher amounts of total Mg, Zn, Mn, Cu and S than the unamended soil, whereas no significant differences in trace-metals were observed for CMC, FWC and UDS treatments.

In conclusion, our preliminary results indicate that co-application of organic amendments with urea-N could potentially fuel CO2 and N2O emissions from soils, thus offsetting any favorable aspects of the aforementioned policies. Organic amendment, urea-N and their interaction were significant factors (p≤0.05) driving CO2 and N2O emissions. The quality and composition of the amendments may stimulate soil microbial N transformations, and further investigation will elucidate the intrinsic role of soil microbes and their dynamics regulating CO2 and N2O emissions from soils.

The research project was supported by the Hellenic Foundation for Research and Innovation (H.F.R.I.) under the 2nd Call for H.F.R.I. Post-Doctoral Research Projects; #01053 awarded to Dr Georgios Giannopoulos. This project was co-implemented with Corteva Agriscience Hellas SA. 

How to cite: Giannopoulos, G., Pasvadoglou, E., Kourtidis, G., Elsgaard, L., Zanakis, G., and Anastopoulos, I.: Co-application of organic amendments and urea-N enhanced CO2 and N2O emissions from a sandy soil; insights of soil N transformations and organic amendments quality., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9598, https://doi.org/10.5194/egusphere-egu23-9598, 2023.

17:00–17:10
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EGU23-4783
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On-site presentation
The increase in N fertilizer application is the key to solving the problem of food security and global warming in rice paddy soils with high initial N concentrations. 
Hyun Ho Lee, Eun Jung Choi, Ok Jung Ju, Chang Oh Hong, and Hojeong Kang

It is essential to reduce methane (CH4) emissions to minimize the contribution of global warming from rice paddies because CH4 contributes approximately 87% to the global warming potential (GWP). An increase in N fertilizer application could reduce CH4 emissions for several reasons: (1) affect the biomass enhancement of crops to store carbon, (2) decrease methanogenesis activity due to increased nitrate respiration, (3) occur nitrate- and nitrite-dependent anaerobic CH4 oxidation. According to the global scale meta-analysis, increasing N application reduces CH4 emissions. However, the reducing effect of nitrogen (N) fertilization on CH4 emissions from rice paddies needs to be confirmed. The changes in CH4 emission induced by N have a reasonably wide margin of error because the research results were not controlled for the direct factors related to CH4 emissions. Hence, although the increased N fertilizer can increase crop productivity and reduce GWP, it is not introduced as an appropriate agricultural practice. 

To elucidate the effects of N fertilization on CH4 emissions from rice paddies, field-based manipulation experiments were conducted in three regions where N fertilizer was applied under the control of the other factors. In addition, we aimed to identify why CH4 emissions differ depending on the amount of N fertilizer through the result of the microbial-mediated CH4 cycle.

Urea was selected as N fertilizer and application rates were at 0, 90, 135, and 180 kg ha-1 (N0, N1, N2, and N3, respectively). Irrigation, rice species (Oryza sativa cv. Samkwang), cultivation period, and input of P, K, Ca, and Si fertilizer were identically managed in 3 sites in Miryang, Wanju, and Hwaseong for three years. DNA/RNA co-extraction was performed using three region’s soil samples in the 3rd year. Real-time qPCR was performed to quantify the mcrA and pmoA gene copy numbers to identify the abundances of methanogens and methanotrophs, respectively.

Cumulative CH4 emissions increased with increasing N fertilizer in Miryang. In contrast, cumulative CH4 emissions significantly decreased with increasing N fertilizer application rates in Hwaseong and Wanju. Especially, N2 and N3 showed CH4 emissions lower than N0 in Hwaseong. In Wanju, the decrease in the abundance of mcrA and subsequently methanogenesis after N1 may cause a reduction in CH4 emissions, while in Hwaseong, the increase in quantification of pmoA and the subsequent higher CH4 oxidation may induce a decline in CH4 emissions. In Miryang, higher mcrA may promote methanogenesis and higher CH4 emissions with an increasing N application. The different responses in methanogens and methanotrophs with different N fertilizer application rates could be due to the initial N concentration. The correlation analysis between initial N including ammonium and nitrate and CH4 emissions from the literature showed a negative relationship at a global scale, suggesting the mechanism based on our experimental results is robust in global rice paddies.

In conclusion, additional N fertilizer application considering the initial N concentration can not only increase crop yield in rice paddies but also reduce global warming by reducing CH4 emissions.

 

How to cite: Lee, H. H., Choi, E. J., Ju, O. J., Hong, C. O., and Kang, H.: The increase in N fertilizer application is the key to solving the problem of food security and global warming in rice paddy soils with high initial N concentrations., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4783, https://doi.org/10.5194/egusphere-egu23-4783, 2023.

17:10–17:20
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EGU23-5614
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ECS
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On-site presentation
Carbon and nitrogen services from cover crops are optimized by including legumes in mixtures 
Chiara De Notaris, Esben Mortensen, Zhi Liang, Maria Vincenza Chiriacò, and Jim Rasmussen

Cover crops are cultivated during unproductive periods to provide ecosystem services, such as preventing nitrogen (N) leaching, and have the potential to increase soil organic carbon (C), thus contributing to climate change mitigation. Their effect on soil C storage depends on C input, which is challenging to quantify due to belowground sampling (roots and C deposited in the soil). Leguminous cover crops (in pure stands or in mixtures) increase the productivity of following main crops due to high N input, but also the risk of N losses, compromising the mitigation effect. As C and N services vary with cover crop type, tradeoffs could be minimized by species selection. The aim of this study was to assess C input from different cover crop species and mixtures, as well as N uptake in their biomass, and their effect on soil mineral N (SMN) and yield of the following crop.

We conducted a field experiment in 2020-2021 at Foulum, Denmark (temperate oceanic climate, sandy loam soil), with seven treatments (five cover crops, control with volunteers, and bare soil) replicated four times. Cover crops undersown in spring barley (Hordeum vulgare L.) in May 2020 were: Lolium perenne L. (ryegrass, RG), Trifolium pratense L. (red clover, RC), Plantago lanceolata L. (plantain, PL) and the mixtures RG-PL and RG-PL-RC. On August 24, 2020, after barley harvest, PVC cylinders (diameter: 29.5 cm, height: 30 cm) were inserted in each plot (25 cm depth) and used for 13C-CO2 multiple-pulse isotopic labeling. Two sessions per week were conducted until cover crop sampling in November 2020, when C and N in above- and belowground biomass, as well C deposited in the soil were determined. Monthly soil sampling (20 cm depth) was performed from August 2020 until April 2021 to assess SMN. Then barley was sown to evaluate cover crops residual effect.

Aboveground biomass was lowest in RG (1.5 Mg ha-1), and highest in RG-PL-RC (5.4 Mg ha-1). Total C input (above- and belowground) ranged from 1.6 to 4.3 Mg ha-1, with RG-PL-RC (highest) being significantly higher than RG-PL and RG (lowest). The same pattern applied to total N input, ranging from 74 to 202 kg ha-1. All cover crop treatments had lower SMN than bare soil and volunteers in August 2020. SMN increased from August until April 2021 with all cover crops except RG, and decreased with bare soil and volunteers. SMN in April was 15 kg ha-1 higher with RC and RG-PL-RC than RG. Barley yield following leguminous cover crops was comparable to plots fertilized with 100 kg ha-1 of mineral N, while non-legumes to 40 kg ha-1. Overall, the mixture with RC provided the greatest C input and positive residual effect. The small change in SMN in April indicate that biomass N was converted into mineral N and taken up by barley during the growing season, thus not increasing the risk of N losses.

How to cite: De Notaris, C., Mortensen, E., Liang, Z., Chiriacò, M. V., and Rasmussen, J.: Carbon and nitrogen services from cover crops are optimized by including legumes in mixtures, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5614, https://doi.org/10.5194/egusphere-egu23-5614, 2023.

17:20–17:30
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EGU23-2450
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ECS
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On-site presentation
A synthesis of regenerative agriculture on soil carbon sequestration in Southeast Asian croplands 
Stanley Tan and Sara Kuebbing

Policymakers and businesses in Southeast Asia are increasingly interested in using carbon markets to encourage adoption of regenerative agriculture practices by farmers. These practices are thought to mitigate climate change by reducing soil carbon loss and enhancing soil carbon sequestration. However, there is uncertainty in the ability of regenerative agriculture practices to increase soil organic carbon (SOC) stocks of croplands. We reviewed 92 empirical studies that investigated the effects of 17 regenerative farming practices across 11 broad categories of crops on SOC stock or content in Southeast Asia. Our synthesis found supporting evidence for the use of organic amendments like biochar, compost, and manure, as well as cover cropping, crop rotation, and conservation tillage to increase SOC. However, studies for practices like addition of compost and manure reported increases in greenhouse gas emissions like methane (CH4) and nitrous oxide (N2O), demonstrating that increases in SOC may be offset by increases in greenhouse gas emissions. Only a few studies measured both the changes in SOC stocks and greenhouse gas emissions and none of the studies completed full greenhouse gas inventories. Estimating the net impact of SOC gains and increase of greenhouse gas emissions will be necessary to understand the overall effect of practices like compost, manure and crop residue incorporation on net atmospheric carbon dioxide concentrations. If these practices are implemented for soil carbon projects, practitioners should anticipate increase in greenhouse gas emissions from soils and implement additional practices, such as alternate wetting and drying, to optimize the climate change mitigation effects of regenerative agriculture. We encourage future research on practices with relatively low numbers of studies and variations in experimental designs and conditions, such as agroforestry and changes in crop residue management. Given the interest in scaling up regenerative agriculture through voluntary carbon markets to boost SOC stocks in croplands, policymakers and businesses can support research in this area by making field-collected data from their projects accessible to researchers to further the study of the impact of these practices across different abiotic conditions and soil management patterns. This would alleviate the paucity and improve the quality of empirical data on regenerative agricultural practices in Southeast Asian croplands, facilitate practice-specific meta-analyses, and ideally begin to optimize climate change mitigation effects of regenerative agriculture.

How to cite: Tan, S. and Kuebbing, S.: A synthesis of regenerative agriculture on soil carbon sequestration in Southeast Asian croplands, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2450, https://doi.org/10.5194/egusphere-egu23-2450, 2023.

17:30–17:40
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EGU23-17251
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On-site presentation
Trade-offs and synergies of carbon sequestration in global agricultural soils: a literature synthesis 
Marta Goberna Estellés and the TRACE-Soils Team

Agricultural management practices aimed at sequestering carbon (C) in soils can have synergies with many agroecosystem services, but may come at the cost of increased greenhouse gas (GHG) emissions and nutrient losses. We performed a systematic literature synthesis to review whether C sequestration practices show synergies with soil structure and soil biota, but generate trade-offs in terms of CO2 and N2O emissions or N and P losses worldwide. We also assessed whether the magnitude of trade-offs and synergies vary across climatic regions and over time.

We performed systematic literature searches in the Web of Science for articles that: 1. experimentally assess the effect of minimising soil disturbance, diversifying agroecosystems, and/or increasing organic matter inputs versus standard practices, and 2. include measurements of C sequestration and at least another response variable related to synergies or trade-offs. We retrieved 771 publications, 537 of which were excluded based on i) the type of article (review, opinion papers), ii) a focus on non-soil habitats, forests or organic soils, or iii) experimental designs not matching our criteria. We included 234 studies that report 572 effects of sustainable practices on 228 sites located in 38 countries. Experiments averaged 10 years of monitoring and the majority reported effects of increasing organic matter inputs and minimising soil disturbance (88%) in temperate and continental climates (75%). Soil organic C increased without compromising crop yields considering all management practices together, i.e. positive effects of sustainable versus standard practices on C sequestration were more frequent than expected by chance. As expected, C sequestration promoted soil biota, but effects were more evident on biomass than on diversity. We also detected synergistic effects on soil aggregation, porosity, water retention and compaction. Negative effects of C retention practices were significant when considering GHG emissions and nutrient losses, particularly for CO2 emissions and mineral N accumulation. However, the magnitude of these trade-offs varied significantly depending on the metrics used to measure them, e.g. field versus lab GHG fluxes. We discuss how these effects vary across management practices, time and space, and review main knowledge gaps detected in the literature.

How to cite: Goberna Estellés, M. and the TRACE-Soils Team: Trade-offs and synergies of carbon sequestration in global agricultural soils: a literature synthesis, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17251, https://doi.org/10.5194/egusphere-egu23-17251, 2023.

17:40–17:50
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EGU23-7256
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ECS
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solicited
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On-site presentation
A global meta-analysis of methane, nitrogen dioxide emission and soil organic carbon changes of grazing grassland soil under different grassland management 
Tong Li and Genxing Pan

Exploring how methane(CH4), nitrogen dioxide(N2O) and soil organic carbon(SOC) content change under different grassland management is significant for mitigating global warming. We conduct a global meta-analysis to figure out the responses of CH4, N2O and SOC content to different management and Random Forest models are used to explore the most important driving factors of the changes. Our results show that grazing can cause SOC lose except in the climate zone Arid, which can increase the SOC content. The emission of CH4 of grazing grassland increases under all grazing intensities and all climate zones. By comparison, the emission of N2O decreases because of grazing activity except the light grazing intensity. As for fertilizer application, all types of fertilizers lead to more CH4 and N2O emission. Among all the fertilizers，cattle urine leads to the most soil N2O emission and chemical fertilizer causes the most CH4 emission. When adding inhibitors, the mitigation effects are significant. They can decrease CH4 and N2O emission 35% and 25% respectively. As for the variables importance in grassland soil greenhouse gas emission, the results of Random Forest models show that the most three important variables in most models are initial SOC content, mean annual precipitation (MAP) and the mean annual temperature(MAT).This study highlights that moderate grazing is better for nature grazing grassland when considering the comprehensive mitigation effect and removing livestock excrement or adding inhibitors are effective ways to mitigate non-CO2 greenhouse gas emission from soil.

How to cite: Li, T. and Pan, G.: A global meta-analysis of methane, nitrogen dioxide emission and soil organic carbon changes of grazing grassland soil under different grassland management, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7256, https://doi.org/10.5194/egusphere-egu23-7256, 2023.

17:50–18:00
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EGU23-13636
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ECS
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On-site presentation
Revealing trade-offs in cropping systems sustainability by piecing together pedo-climatic datasets and agronomic knowledge with fuzzy logic 
Roberta Calone, Angela Fiore, Maria Luz Cayuela, Alessandra Lagomarsino, Joël Léonard, Fabien Ferchaud, Marco Acutis, Elena Valkama, Guido Pelis, and Simone Bregaglio

Agriculture is among the sectors most affected by climate change and, simultaneously, is the primary responsible for anthropogenic non-CO2 greenhouse gas (GHG) emissions worldwide. Nonetheless, the actual estimation of global GHGs emissions due to agricultural activities is still subject to significant uncertainty.  The Intergovernmental Panel on Climate Change (IPCC) and the Water Footprint Network (WFN) provide a set of equations and emission factors, the so-called Tier 1, for separately estimating carbon stock changes, N2O emissions, and NO3 leaching losses under a limited set of pedo-environmental conditions and agricultural Soil Management Strategies (SMS, i.e., crop choice, fertilization, irrigation, and soil tillage). However, the Tier 1 methodologies do not explicitly consider the multi-faceted interactions among SMS, pedo-environmental variability, and nitrogen and carbon fluxes. Indeed, current research demonstrated that increased N2O emissions and NO3 leaching due to these interactions could offset potential climate-positive effects due to carbon farming.

A Europe-wide policy approach is urgently needed to assess the effects of SMS on nitrogen and carbon fluxes and fulfil the Sustainable Development Goals of the UN's 2030 Agenda. ∑ommit project, financed by the European Joint Programme SOIL, aims to generate a robust indicator to predict trade-offs and synergies between soil carbon sequestration, GHGs emissions, and N leaching losses to identify the best SMS according to their application context. The project harmonized multiple data sources as the 2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories (IPCC 2019), the WFN Guidelines for grey water footprint accounting (Franke et al 2013), and the Italian National Institute of Statistics (ISTAT), in order to estimate the effects of SMS on four trade-off components: crop yield, soil carbon sequestration, N2O emission, and NO3 leaching losses. Each row of the data frame, the case scenario, represented a combination of soil × climate × SMS, whose effect on the trade-off components was either inferred from the Tier 1 methodologies or derived from meta-analyses and experts’ opinions. Trade-off components were aggregated into a composite index (∑ommit index) using a fuzzy logic model. The index ranges from 0 (bad) to 1 (good), providing a synthetic and comprehensive measure of the environmental impact of SMS in different pedo-climatic conditions. Besides giving an immediate measure of the system performance and facilitating the comparison of alternative SMS, the index lends itself to be disentangled to trace the effect of specific management practices on key aspects of system sustainability. The trade-off system has been also tested with data from long-term experiments and model simulations (STICS and Armosa) to identify the best-performing SMS in different application contexts. The system demonstrated its sensitivity to modulate the expression of trade-off components coherently using simulated and observed data as input. The aggregation procedure smoothed the magnitude of the model errors in reproducing experimental data, leading to lower uncertainty in the index values than in the single trade-off components. This result paves the way for an advised use of crop models to speed up the identification of the best SMS and design more sustainable cropping systems.

How to cite: Calone, R., Fiore, A., Cayuela, M. L., Lagomarsino, A., Léonard, J., Ferchaud, F., Acutis, M., Valkama, E., Pelis, G., and Bregaglio, S.: Revealing trade-offs in cropping systems sustainability by piecing together pedo-climatic datasets and agronomic knowledge with fuzzy logic , EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13636, https://doi.org/10.5194/egusphere-egu23-13636, 2023.

Posters on site: Mon, 24 Apr, 10:45–12:30 | Hall X3

The posters scheduled for on-site presentation are only visible in the poster hall in Vienna. If authors uploaded their presentation files, these files are linked from the abstracts below, but only on the day of the poster session.
Chairpersons: Mart Ros, Eugenio Diaz Pines
X3.123
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EGU23-1543
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ECS
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On-site presentation
Nitrous oxide and methane emissions are affected by soil tillage systems and crop diversity in the Brazilian Savanna 
Jorge Luiz Locatelli, Jéssica Heloiza Coutinho, Igor Eduardo Martins Menezes, Francisco William Rodrigues da Silva, Leticia Thomaz Cipriani, Diana Fernada Quiceno Torres, Lina Maria Tierradentro Rojas, Cassiano Garcia Roque, Edicarlos Damacena de Souza, Maurício Roberto Cherubin, and Carlos Eduardo Pellegrino Cerri

Population growth associated with the increasing demand for resources around the globe has increased greenhouse gas (GHG) emissions, leading to the climate change process. In this study, we assessed the impact of agrosystems intensification on N2O and CH4 emissions in the Brazilian Savanna. We selected two long-term experiments located in Costa Rica – MS and Itiquira – MT, which consisted of soil tillage systems (conventional (CT) and no tillage (NT) systems) and levels of crop diversification with cover crops (e.g., Brachiaria sp., Crotalaria sp., Pennisetum sp.) in soybean-cotton-based cropping systems. Gas emissions were monitored for 8 months (February 2022 to October 2022). N2O and CH4 fluxes were calculated following the linear changes in the concentration of each gas, and cumulative emissions were estimated after extrapolation from hourly to daily fluxes. Data were subjected to analysis of variance, and means were compared by Tukey's test (p<0.05). In Costa Rica - MS, CH4 fluxes varied between -30 and 50 µg m-2 h-1 of CH4-C and were greatly affected by rainfall seasonality. Cropping systems affected cumulative emissions, with soybean + cotton under CT and soybean + cotton + maize presenting emissions of 0.13 and 0.27 kg ha-1 of CH4-C, respectively. Soybean + cotton under NT and the treatments with cover crops (soybean + cotton + Brachiaria sp., and soybean + cotton + rattlebox) promoted CH4 uptake, sequestering up to 0.6 kg ha-1 of CH4-C. N2O fluxes were mostly affected by N fertilization. Peaks up to 270 µg m-2 h-1 of N2O-N were observed, most associated with soybean + cotton + maize treatment, and soybean + cotton under CT. The highest cumulative N2O emissions were observed at soybean + cotton + maize and soybean + cotton + Brachiaria sp. treatment (0.88 kg ha-1 of N2O-N on average). Soybean + cotton under CT and NT systems, and soybean + cotton + rattlebox showed an average cumulative emission of 0.43 kg ha-1 of N2O-N. At Itiquira – MT, CH4 fluxes also were affected by rainfall seasonality, with values ranging between -40 and 90 µg m-2 h-1 of CH4-C. Cumulative CH4 emissions were significantly affected by the treatments, with the highest emissions at soybean + maize succession (i.e., 0.36 kg ha-1 of CH4-C). The succession between soybean + Brachiaria sp. and the other crop rotations involving rattlebox and millet did not differ from each other, presenting an average uptake of 0.13 kg ha-1 of CH4-C. For N2O-N, the fluxes were highly responsive to N fertilization in maize, presenting peaks up to 75 µg m-2 h-1 of N2O-N. Cumulative N2O emissions, however, were reduced (0.18 kg ha-1 ofN2O-N) only at soybean + rattlebox + maize + Brachiaria sp., which was 2.7 times lower than the cumulative emissions found at soybean + maize, soybean + Brachiaria sp., and soybean + rattlebox + maize + Brachiaria sp. for one year period. Overall, our results suggest that cropping intensification in the Brazilian Savanna is an efficient strategy to reduce CH4 and N2O emissions, contributing to tackling the climate change process. 

How to cite: Locatelli, J. L., Coutinho, J. H., Menezes, I. E. M., da Silva, F. W. R., Cipriani, L. T., Torres, D. F. Q., Rojas, L. M. T., Roque, C. G., de Souza, E. D., Cherubin, M. R., and Cerri, C. E. P.: Nitrous oxide and methane emissions are affected by soil tillage systems and crop diversity in the Brazilian Savanna, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1543, https://doi.org/10.5194/egusphere-egu23-1543, 2023.

X3.124
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EGU23-5823
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ECS
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On-site presentation
Effects of biodegradable and plastic mulches on soil biogeochemical cycles in an agricultural system 
Alessia Esposito, Enrica Picariello, Luigi Morra, and Flavia De Nicola

Agricultural soils perform important ecological functions and agricultural practices affect the maintenance of these functions. Mulching is an agronomic technique, consisting of covering the soil with a protective layer of natural or artificial materials. Mulching influences soil temperature and moisture, promotes the development of microorganisms, allows the release of nutrients and reduces the development of weed species, improving crop growth. The aim of the research was to evaluate the effect of Low-density polyethylene based mulching film (LDPE) and biodegradable Mater-bi® (thermoplastic starch) based mulching films on soil organic matter and microbial enzyme activities linked to biogeochemical cycles of C, N and P.

The experimental field was established at an organic farm (Capua, Caserta, Southern Italy), under a greenhouse environment. According to organic farming management, soil was amended with green manure and on farm compost. The experiment was carried out in a randomized block design with five treatments replicated four times: soil covered with LDPE film, soil covered with Mater-Bi® films of 3 different thicknesses (18, 21, 25 μm), bare soil in area not mulched under the same tunnel as control. The films were placed on soil surface in October 2021, then strawberry was planted and cultivated until June 2022. After 7 months, in correspondence with the maximum strawberry production, soil was sampled (at 20 cm depth), sieved (2 mm) and samples analysed for organic matter content (by calcination in muffle) and enzyme activities (hydrolase, β-glucosidase, phosphatase and β-glucosaminidase by spectrophotometric method).

The soil organic matter content showed higher value in control soil (4.22%) respect to soil covered with LDPE and Mater-Bi® films 25 µm (on average 3.56%). The β-glucosidase activity showed the highest value in the soils covered with Mater-bi® 18 µm, whereas the hydrolase, phosphatase and β-glucosaminidase showed no significant differences among treatments. Therefore, the application of biodegradable plastic films did not show clear effect on soil organic carbon stock after 7 months, likely due to the high organic matter content characterizing this soil. However, as the enzyme β-glucosidase is involved in the C-cycle, the results indicated a possible effect on this activity due to a faster degradation of the thinnest biodegradable plastic film (Mater-bi® 18 µm). Enzyme activities are sensitive indicators and provide rapid responses compared to soil chemistry analyses, in particular β-glucosidase is significantly correlated with agronomic practices, and it is able to quickly detect changes in soil management. The study of enzyme activities as indicators of soil quality can provide useful data to implement agricultural sustainable management strategies.

How to cite: Esposito, A., Picariello, E., Morra, L., and De Nicola, F.: Effects of biodegradable and plastic mulches on soil biogeochemical cycles in an agricultural system, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5823, https://doi.org/10.5194/egusphere-egu23-5823, 2023.

X3.125
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EGU23-7103
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On-site presentation
Can cup-plant (Silphium perfoliatum L.) as a perennial bioenergy crop surpass silage maize (Zea mays L.) for C sequestration? 
Khatab Abdalla and Johanna Pausch

Intensified silage maize (Zea mays L.) cultivation has led to several environmental problems such as high greenhouse gas emissions and groundwater pollution, thus further amplifying climate change. Therefore, alternative crops with high carbon (C) sequestration capacities are crucial for sustainable bioenergy production, particularly those that can cope with extreme climate events, such as drought stress. Therefore, this study aimed to evaluate the potential of the perennial cup-plant (Silphium perfoliatum L.) as a promising alternative for silage maize to increase soil C input and reduce C output (as CO2) under optimum watering and drought conditions. For this purpose, a lysimeter experiment comparing these crops subjected to two watering regimes (well-watered and drought-stressed), was set up at the botanical garden of the University of Bayreuth, Germany. Soil respiration was correlated to soil moisture and temperature, biomass (aboveground and belowground), soil C and nitrogen (N), and dissolved organic C (DOC) and inorganic C in the leachates. Soil CO2 efflux was measured using a Licor-6400XT gas exchange system (LI-COR, Lincoln, NE, USA)) fitted with a soil chamber over three consecutive years. The final cumulative CO2 efflux was greater by 29% under drought-stressed cup-plant than in drought maize, which was explained by the greater belowground biomass production under cup-plant. Cup-plant increased root biomass by 143% (0.86±0.26 vs 2.08±0.33 kg m-2) compared to silage maize, thus, implying a higher contribution of root respiration to the total soil respiration under cup-plant. Despite the soil respiration and DOC leaching being higher for cup-plant than maize, cup-plant increased soil C (by 4%) and N content (by 14%), after only two years of cultivation. Even though root respiration and enhanced microbial activity result in higher soil respiration and C mineralization, the continuous supply of fresh C via the root litter and rhizodeposits of the perennial cup-plant suggests long-term effective C farming and demonstrates the potential of the cup-plant as an ecological alternative to silage maize.

Keywords: Climate change; soil respiration; carbon sequestration; bioenergy crops; leachates

 

How to cite: Abdalla, K. and Pausch, J.: Can cup-plant (Silphium perfoliatum L.) as a perennial bioenergy crop surpass silage maize (Zea mays L.) for C sequestration?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7103, https://doi.org/10.5194/egusphere-egu23-7103, 2023.

X3.126
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EGU23-8576
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On-site presentation
Linking land use and peat soil distribution and properties in agricultural lands of Latvia
(withdrawn)
Raimonds Kasparinskis, Ivo Vinogradovs, Kristīne Afanasjeva, Andris Avotiņš, Baiba Dirnēna, Imants Kukuļs, and Oļģerts Nikodemus
X3.127
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EGU23-11122
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ECS
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On-site presentation
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The legacy effect of long-term management on greenhouse-gas fluxes in European croplands. 
Ulises Ramon Esparza-Robles, Eugenio Díaz-Pinés, and Alessandra Lagomarsino

In the frame of climate change mitigation, the effect of agricultural practices on soil organic carbon (SOC) stocks has been widely studied in different pedoclimatic conditions across Europe. Practices that have been identified as generally having a positive effect on SOC stocks include those increasing carbon inputs to the soil via external organic matter or via incorporation of crop residues. These practices also modify the soil N2O and CH4 fluxes; this is highly relevant for estimating the overall effect of management strategies on the soil greenhouse gas (GHG) balance, but so far, this aspect has not been assessed comprehensively. In this work, we make use of long-term experiments covering a large range of soil and environmental conditions in Europe. Further, the experiments were selected based on the management practices under investigation (addition of organic matter, crop residue management) and access to data on SOC stock changes as affected by management. Undisturbed soil samples were investigated for non-CO2 fluxes under controlled conditions. As research within the scope of global change, soils underwent a drying-and-rewetting cycle to study the soil response to extreme events in relation to the organic matter inputs. Our lab data provide relevant information on soil non-CO2 fluxes, which will be integrated with SOC stock change data, field GHG flux data and ancillary soil information. Overall, we will increase our understanding of soil processes towards identifying and promoting win-win scenarios between greenhouse gas fluxes and soil carbon storage in European croplands.

How to cite: Esparza-Robles, U. R., Díaz-Pinés, E., and Lagomarsino, A.: The legacy effect of long-term management on greenhouse-gas fluxes in European croplands., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11122, https://doi.org/10.5194/egusphere-egu23-11122, 2023.

X3.128
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EGU23-11415
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ECS
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On-site presentation
Trade-offs between carbon sequestration by cover crops and off-season nitrous oxide emissions in hemiboreal cereal production 
Sigrid Trier Kjær, Rong Lang, Ievina Sturite, and Peter Dörsch

The use of cover crops in cereal production as a climate smart agricultural practice is generally used to increase carbon sequestration in soils. However, increased plant biomass in wintertime can trigger N2O emissions due to decay during freeze-thaw cycles. So far little is known about N2O winter emissions from cover crops which, in the worst case, could cancel out the carbon gain by cover crops. Here we report N2O emissions from a two-year field experiment in SE Norway with barley and various cover crops (perennial and Italian ryegrass, oilseed radish, summer and winter vetch, phacelia and a mixture of different herbs) measured against controls without cover crops. A field robot was used for measuring N2O emissions at high temporal resolution during off-season, i.e., the period from cereal crop harvest to cereal crop sowing. During the first winter, the snow cover was poor and the significantly higher N2O emissions were measured from oilseed radish during spring thaw whereas perennial ryegrass reduced emissions. A second winter is measured and N2O emissions from both years will be presented. In addition, continuous measurements are needed to assess the effect of diurnal freeze-thaw cycles on N2O emissions before scaling up to annual N2O emission fluxes and comparing with C sequestration.

How to cite: Kjær, S. T., Lang, R., Sturite, I., and Dörsch, P.: Trade-offs between carbon sequestration by cover crops and off-season nitrous oxide emissions in hemiboreal cereal production, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11415, https://doi.org/10.5194/egusphere-egu23-11415, 2023.

X3.129
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EGU23-8709
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On-site presentation
Soil respiration in a traditional olive grove in the southeast of Spain 
Sergio Aranda-Barranco, Penelope Serrano-Ortiz, Andrew Stephen Kowalski, and Enrique P Sánchez-Cañete

Olive groves occupy a large area in the Mediterranean and their management has repercussions on the carbon cycle in this region.  Weed suppression is the most common management in this crop, but its implications for soil respiration (Rsoil) are not well estimated due to the lack in continuous Rsoil measurements. In this research we present a full year of Rsoil in an irrigated olive grove in which a glyphosate-based herbicide was applied to prevent spontaneous weeds (conventional management). For that, an automatic multi-chamber Rsoil system was used (LI-8100 + LI-8150 with 6 chambers, Li-Cor). In addition, soil temperature (Tsoil) and soil water content (SWC) were measured next to each chamber. To study the influence of olive trees on Rsoil, 3 chambers were placed near the olive trunk and another 3 in the middle of the alleys.

Results show seasonal and spatial variability, with higher Rsoil in warm months and lower Rsoil in cold months. Also, Rsoil near the trunk was always larger than in the alleys. The spatial difference increased in the cold months. Diurnal variability was observed with higher Rsoil as the soil temperature increased in the alleys, but this was not observed near the trunks. Under the canopy, a decrease in the Rsoil is observed as the VPD increases, suggesting a major contribution of autotrophic respiration under the canopy. In addition, there is no positive and negative relationship with temperature and SWC under the canopy, while in the alleys, a strong hysteresis occurs in some periods. Finally, rain events were followed by Rsoil peaks. However, low intensity and short duration rain pulses did not manifest on the ground under the olive canopy, so interception is inhibiting this process in part of the agrosystem.

This work was supported by the projects PID2020-117825GB-C21 & PID2020-117825GB-C22 (INTEGRATYON3), B-RNM-60-UGR20 (OLEAGEIs), P18-RT-3629 (ICAERSA) and PPJIB2022-08 funded by University of Granada.

How to cite: Aranda-Barranco, S., Serrano-Ortiz, P., Kowalski, A. S., and Sánchez-Cañete, E. P.: Soil respiration in a traditional olive grove in the southeast of Spain, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8709, https://doi.org/10.5194/egusphere-egu23-8709, 2023.

X3.130
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EGU23-12351
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ECS
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On-site presentation
Effect of agricultural measures on CO2-sequestration, N2O emissions and soil functions 
Thalisa Slier, Dorien Westerik, Jan Peter Lesschen, Chris Koopmans, Jonas Schepens, Wieke Vervuurt, Gerard Velthof, and Jennie van der Kolk

In light of the Paris Climate Agreement, the Dutch government has set mitigation targets for the emission of greenhouse gases (GHGs). One of the targets for the Dutch agricultural sector is to sequester an additional 0.5 Mton CO­2-equivalents per year on mineral agricultural soils, from 2030 onwards. Additionally, all Dutch agricultural soils should be sustainably managed by then. The research programme Smart Soil Use aims to determine to what extent it is possible to meet these goals. Since 2018, various projects and experiments investigated (sets of) measures or management practices that have the potential to store carbon (C). For 12 agricultural measures, C-sequestration potential was determined based on a combination of long-term field experiments in which soil C has been measured and C-modeling using the RothC model. Additionally, trade-offs of these measures with the GHG nitrous oxide (N2O) were monitored in the field experiments, using a static flux chamber setup. In addition, various soil parameters from the BLN (Soil Indicators for Dutch Agricultural Soils) were measured to assess the impact on other soil functions. Here, we present an integrative summary of the results, with for each measure, the C-sequestration potential, the possible trade-off with N2O emissions, and the consequences for soil functions, such as soil fertility and soil biodiversity. Based on the modelling results, it is possible to sequester an estimated 0.9 Mton CO2 yearly, using a combination of measures and assuming a maximum implementation of 100%. The first results show that certain measures increase N2O emissions, but that, overall, a possible trade-off to N2O emissions will not exceed the benefit of C-sequestration on the short term. Based on a qualitative analysis, most of the measures have a positive or neutral effect on soil functions.

How to cite: Slier, T., Westerik, D., Lesschen, J. P., Koopmans, C., Schepens, J., Vervuurt, W., Velthof, G., and van der Kolk, J.: Effect of agricultural measures on CO2-sequestration, N2O emissions and soil functions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12351, https://doi.org/10.5194/egusphere-egu23-12351, 2023.

X3.131
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EGU23-12322
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ECS
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On-site presentation
Minor effects of no-till treatment on GHG emissions of boreal cultivated peat soil 
Henri Honkanen, Hanna Kekkonen, Jaakko Heikkinen, and Kristiina Lång

Greenhouse gas emissions of a spring cereal monoculture under conventional tillage and no-till treatments were measured in a peatland in Southwestern Finland for three years in 2018-2021. Nitrous oxide (N2O), carbon dioxide (CO2) and methane (CH4) fluxes were measured with an opaque chamber technique approximately biweekly throughout the years. During the growing season, canopy net ecosystem exchange (NEE) was measured with a transparent chamber technique and hourly ecosystem respiration (ER) and gross photosynthesis (GP) were modelled with empiric models. On average, the annual emissions were 6.4±2.4 Mg CO2-C ha -1 yr-1, 7.6±3.5 kg N2O-N ha-1 yr-1, and -0.35±0.42 kg CH4-C ha-1 yr-1 for NEE, N2O and CH4, respectively. The effect of no-till management on the GHG balance was non-consistent through years and thus generally of minor significance. No-till reduced annual CO2 emissions by 24% in 2019 and N2O emissions by 33% in 2020 compared to conventional tillage while there were no differences in other years. Measured differences in ER occurred mostly during the winter periods, especially after ploughing. The results indicated that no-till may reduce CO2 and N2O emissions from cultivated peat soil, but it does not lead to large consistent reductions during the first years of NT management.

How to cite: Honkanen, H., Kekkonen, H., Heikkinen, J., and Lång, K.: Minor effects of no-till treatment on GHG emissions of boreal cultivated peat soil, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12322, https://doi.org/10.5194/egusphere-egu23-12322, 2023.

X3.132
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EGU23-13422
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ECS
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On-site presentation
Nitrous oxide emissions and ammonia volatilisation in a field experiment with different organic and inorganic fertilisers with biochar combinations 
Ferdinand Hartmann, Celia Fernandez Balado, and Rebecca Hood-Nowotny

Agriculture is contributing majorly to anthropogenic greenhouse gas emissions and pollution. 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. Further, to keep economic (fertiliser prizes drastically increased due to the energy crisis) and ecological (Haber Bosch process is very energy intense and still based on fossil fuels) costs for fertiliser low, a high fertilizer use efficiency is worthwhile. Therefore, advances in agricultural practices reducing atmospheric N-losses are highly relevant in order to mitigate global warming and related environmental issues. Biochar can reduce N2O emissions and NH3 volatilisation by influencing various soil properties. However, this depends on pedoclimatic conditions, the applied biochar, and other agricultural practises. To refine biochar’s use to mitigate atmospheric N-losses more data for different soils and fertilizers are needed, especially from experiments coming close to common agricultural settings. In a field experiment we cultivated corn (Zea mays) with different organic (external organic matter, EOM) and inorganic fertilizers with and without biochar combinations. The original soil was loamy, low in organic carbon and slightly acidic. Our results are showing significant and substantial reductions in N2O emissions and NH3 volatilisation within the first weeks after fertiliser application. This pattern was especially observed for synthetic fertiliser. We suggest that biochar is a suitable amendment for fertilisation, especially for highly productive agroecosystems where high amounts of fertiliser are needed, to reduce environmental impact and increase fertiliser use efficiency.

How to cite: Hartmann, F., Fernandez Balado, C., and Hood-Nowotny, R.: Nitrous oxide emissions and ammonia volatilisation in a field experiment with different organic and inorganic fertilisers with biochar combinations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13422, https://doi.org/10.5194/egusphere-egu23-13422, 2023.

X3.133
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EGU23-13368
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On-site presentation
N and P nutrient leaching from long-term slurry application on permanent grassland on clay loam soil 
Zizhou Qi, Jonathan Holland, and Magdalena Necpalova

Over one-third of rivers and a quarter of lakes in Ireland are failing to meet their environmental quality standards for nutrients. This is impacting Ireland’s goal to improve water quality and achieve its EU Water Framework Directive targets. Nitrogen (N) and phosphorus (P) leached from different forms of fertilizer application may contribute to groundwater and surface water contamination causing numerous environmental issues in the agroecosystem and health problems in human beings. There is a lack of knowledge on the magnitude of the effects of the nutrient management strategies and their long-term implementation on N and P nutrient leaching from the soil to the groundwater and surface waters in Ireland. The accurate optimization of the nutrient management strategies requires monitoring of soil water concentrations under the range of management strategies and quantification of the N and P leaching from the soil profile.

The objective is to study the N and P leaching in organic and inorganic forms from a long-term application of cattle and pig slurry and mineral NPK fertilizer over the drainage seasons 2021/22 in Hillsborough (54°28′ 0′′ N, 6°6′ 0′′ W), Northern Ireland, UK. The long-term experiment in Hillsborough was set up in 1970 to measure the effects of frequent applications of organic and inorganic nutrients on plant productivity and soil biogeochemistry. It was set up in a split-plot design with nutrient management as a main factor and grass-species biodiversity (rye-grass vs multi-species sward treatment) as a subplot factor replicated three times. The multispecies sward was reseeded (05/08) after ploughing (31/07) in spring 1969. Leaching was measured in six nutrient management (control, synthetic fertilizer, pig and cattle slurry with high and low rates) and both biodiversity treatments. Soil solution from an 80 cm dept was extracted using suction cups every ten days over a 5-month drainage period. N and P leaching were quantified from nutrient concentrations of various species multiplied by an effective rainfall obtained through Schulte’s Soil Moisture Deficit hybrid model. The total N, total oxidized N, ammonium, total P, and dissolved reactive P have been analyzed, the N and P losses have been quantified for the above species. Nutrient concentrations and losses were analyzed as repeated measures with a linear mixed effects model in R.

Most of the concentrations of various nutrient species were affected by an interactive effect between nutrient management and biodiversity level. The influence of permanent grassland renovation and reseeding is also evident. However, the concentrations are low, below the water quality thresholds defined by water quality legislation and national background levels in groundwater or surface waters despite the high rates of continuous nutrient applications for over 50 years. This is likely associated with the high natural attenuation capacity of the soil driven by clay-loam texture. The data will be further used in the optimization of the nutrient management strategies using an ecosystem process-based model DayCent. We believe that the results of this study will have direct implications for agri-environmental policies in the Rep. of Ireland and in the UK.

How to cite: Qi, Z., Holland, J., and Necpalova, M.: N and P nutrient leaching from long-term slurry application on permanent grassland on clay loam soil, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13368, https://doi.org/10.5194/egusphere-egu23-13368, 2023.

X3.134
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EGU23-16366
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On-site presentation
The SOMMIT Project: SUstainable Management of soil Organic Matter to MItigate Trade-offs between C sequestration and nitrous oxide, methane and nitrate losses 
Eugenio Diaz-Pines, Frida Keuper, Felipe Bastida, Simone Bregaglio, Maria Luz Cayuela, Claudia Di Bene, Fabien Ferchaud, Rossana Ferrara, Angela Fiore, Joel Léonard, Peter Maenhout, Rok Mihelič, Adam O´Toole, Marjetka Suhadolc, Alina Syp, Elena Testani, Elena Valkama, and Alessandra Lagomarsino

Within the context of climate change there is increasing focus on the implementation of agricultural practices which contribute to soil C sequestration (Cseq) to mitigate rising atmospheric CO2 levels. The agricultural sector is, however, also the largest global contributor to anthropogenic non-CO2 GHGs. N2O and CH4 emissions contribute substantially to the Earth’s radiative forcing and even small impacts on their fluxes could hamper climate change mitigation efforts. While it is known that Soil Management Strategies (SMS) aimed at increasing Cseq in agricultural soils also affect soil N2O and CH4 fluxes and N losses through leaching, data and knowledge are still fragmented. Thus, a Europe-wide policy approach to the resulting trade-offs is urgently needed, given the high global warming potential of N2O. Mitigation effects of agricultural practices enhancing Cseq can largely be offset if N2O emissions increase but SMS enhancing Cseq and reducing non-CO2 GHG emissions imply a “double-win” situation for climate change mitigation. Integrated, coupled investigations are still scarce, with only a few studies addressing trade-offs comprehensively.

Overall, the ∑OMMIT project evaluates trade-offs and synergies between soil C sequestration, nitrous oxide, methane and nitrate losses as affected by soil management options aimed at increasing soil C storage. The integrated and interdisciplinary approach will address the main pedo-climatic conditions and farming systems in Europe, through 1) synthesis and meta-analysis of available literature and data; 2) targeted, novel measurements on key long-term experiments; and 3) simulation of long-term agro-ecological system responses to contrasting management options. Moreover, obtained data will be synthesized through a fuzzy-expert system which will allow for 4) evidence-based identification of optimal strategies for mitigation of trade-offs, and 5) effective stakeholders’ involvement. Overall, we aim at increasing our understanding on the mechanisms and driving forces affecting N2O and CH4 fluxes. Our approach works from different perspectives, allowing a cross-validation on the observed interactions and feedbacks. Here, the current status of the ∑OMMIT project will be presented. We will show the most important results obtained so far and will discuss the implications for soil management strategies in the agricultural European context.

How to cite: Diaz-Pines, E., Keuper, F., Bastida, F., Bregaglio, S., Cayuela, M. L., Di Bene, C., Ferchaud, F., Ferrara, R., Fiore, A., Léonard, J., Maenhout, P., Mihelič, R., O´Toole, A., Suhadolc, M., Syp, A., Testani, E., Valkama, E., and Lagomarsino, A.: The SOMMIT Project: SUstainable Management of soil Organic Matter to MItigate Trade-offs between C sequestration and nitrous oxide, methane and nitrate losses, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16366, https://doi.org/10.5194/egusphere-egu23-16366, 2023.

Posters virtual: Mon, 24 Apr, 10:45–12:30 | vHall SSS

The posters scheduled for virtual presentation are visible in Gather.Town. Attendees are asked to meet the authors during the scheduled attendance time for live video chats. If authors uploaded their presentation files, these files are also linked from the abstracts below, but only on the day of the poster session. The button to access Gather.Town appears just before the time block starts.
Chairpersons: Eugenio Diaz Pines, Ana Meijide
vSSS.13
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EGU23-5895
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Virtual presentation
Trade-off between C sequestration and GHGs fluxes in a long-term maize crop under contrasting management options 
Alessandra Lagomarsino, Claudia Becagli, Alessandro Casagli, Filippo Rocchi, Isabella De Meo, Giorgio Moretti, and Roberta Pastorelli

Monitoring of long-term responses of crop systems to contrasting management options is of key importance to assess the capacity of agriculture to mitigate climate changes, by increasing carbon sequestration and reducing green-house gases emissions. To this aim, long-term trials are fundamental since allow the evaluation of the trade-off between processes occurring at different time frames, such as C storage and CO2, CH4 and N2O emissions.

Within EJP SOIl – ∑OMMIT project a long-term trial established in 1994 was selected in a Mediterranean mountain area in Tuscany (Italy), comparing maize monoculture vs. rotation at contrasting tillage intensities (deep ploughing vs. disk harrowing).

Fluxes of CO2, CH4 and N2O, have been measured in 2021 growing season together with climate factors, inorganic N availability and microbial communities’ composition, and compared with C accumulated in the last 20 years.

The objectives of the monitoring were to assess the impact of cropping systems at low and high tillage intensities on i) the trade-offs between long-term C accumulation and GHGs emissions, and ii) the microbial community composition and activity. Moreover, the work aimed at improving the understanding of the main abiotic and biotic drivers of GHGs exchanges considering the plant-soil-atmosphere integrated system.

The stage of crop rotation had the highest impact on both C storage and GHGs fluxes, showing larger C exchanges and lower N2O emissions with leguminous than maize. Tillage intensities showed not significant changes in CO2 emissions and a slight increase with deep ploughing with respect to disk harrowing, which also experienced a larger C accumulation. All cropping systems, independent of tillage and rotation phase, acted as sinks for CH4.

The soil microbial communities resulted influenced by the different cropping systems. In particular, significant differences were highlighted in the abundance of microbial groups involved in denitrification and nitrification processes.

How to cite: Lagomarsino, A., Becagli, C., Casagli, A., Rocchi, F., De Meo, I., Moretti, G., and Pastorelli, R.: Trade-off between C sequestration and GHGs fluxes in a long-term maize crop under contrasting management options, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5895, https://doi.org/10.5194/egusphere-egu23-5895, 2023.

vSSS.14
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EGU23-7372
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ECS
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Virtual presentation
TRUESOIL Project: Understanding Trade-offs and Dynamic Interactions between SOC Stocks and GHG Emissions for Climate Smart Agrisoil Management 
Antonios Apostolakis, Paulina Englert, Peter Dörsch, Oslan Jumadi, Ibrahim Khalil, Katja Klumpp, Sergio Morales, Chukwuebuka Christopher Okolo, Bruce Osborne, Jorge Perez-Quezada, Mari Philatie, Gabriela Posse, Ileana Frasier, Silvina Restovich, Penélope Serrano-Ortiz, Sigrid Trier Kjær, Pauliina Turunen, Bas van Wesemael, Frank Verheijen, and Ana Meijide and the Antonios Apostolakis

According to the Paris Agreement 2015, increased carbon sequestration by soils is a vital option for climate change mitigation and, simultaneously, improves soil health and food security. Agricultural soils are globally depleted in soil organic carbon and, therefore, exhibit a high potential for carbon sequestration. Various agroecological practices aim to increase or maintain soil organic carbon through increasing carbon inputs in the soil (e.g., amendments, plant residues, cover crops) and/or through reducing carbon losses (e.g., reduced or no tillage, adapted grazing). However, these practices have the potential to increase greenhouse gas emissions, which limits their effectiveness in terms of climate change mitigation.

The EJP-SOIL project TRUESOIL (2022-2025) studies trade-offs between agricultural management practices aiming at increasing carbon sequestration and reducing greenhouse gas emissions from agroecosystems across crops, soil properties and climates. TRUESOIL investigates biotic and abiotic drivers of soil organic carbon dynamics and greenhouse gas emissions under field conditions in experimental croplands and grasslands in 13 countries and five continents, covering broad environmental and pedogenic gradients. Further, TRUESOIL investigates the impact of experimental droughts under rainout shelters on crop yields, soil organic carbon pools and greenhouse gas emissions. The project will improve the mechanistic understanding of soil organic matter and greenhouse gas interactions and predict trade-offs between management-induced soil organic carbon changes and greenhouse gas emissions under future climatic conditions. Finally, laboratory incubations will address the role of microbial community composition as shaped by agricultural management in soil organic matter stabilization and nutrients turnover.

TRUESOIL moves beyond bulk soil organic carbon stocks and studies the operational carbon pools of particulate and mineral-associated organic matter. While multiple greenhouse gases are targeted, a focus is given on N2O due to its high warming potential and its relative uncertainty in flux calculations compared to CH4 and CO2 gases. Spanning from boreal to tropical climates, TRUESOIL sites cover a mean annual temperature range from 6 to 27°C and a precipitation range from 300 to 1150 mm. Similarly, soil organic carbon concentrations ranged from 1% to 10% with some sites greatly depleted in soil organic carbon, while others not and without signs of carbon saturation. Based on its wide geographical coverage, the TRUESOIL project will provide recommendations on management measures relevant to multiple stakeholders, from farmers to policy makers.

How to cite: Apostolakis, A., Englert, P., Dörsch, P., Jumadi, O., Khalil, I., Klumpp, K., Morales, S., Okolo, C. C., Osborne, B., Perez-Quezada, J., Philatie, M., Posse, G., Frasier, I., Restovich, S., Serrano-Ortiz, P., Kjær, S. T., Turunen, P., van Wesemael, B., Verheijen, F., and Meijide, A. and the Antonios Apostolakis: TRUESOIL Project: Understanding Trade-offs and Dynamic Interactions between SOC Stocks and GHG Emissions for Climate Smart Agrisoil Management, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7372, https://doi.org/10.5194/egusphere-egu23-7372, 2023.

vSSS.15
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EGU23-12433
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ECS
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Virtual presentation
Effects of biogas digestate and winter crops on dissolved organic carbon and nitrates fluxes in soil. 
Anne-Flore Didelot, Emilie Jardé, Thierry Morvan, Florian Gaillard, Marine Liotaud, and Anne Jaffrezic

The anaerobic digestion industry is currently in development and enables the energetic valorization of organic waste products (OWP) to generate biogas. A co-product of this process, digestate, is more and more produced and can be recycled on agricultural lands as a low-cost alternative to mineral fertilizers. Thus, the organic carbon (C) it contains could improve the soil quality and store C in subsoil through dissolved organic C (DOC) transfers. Biogas digestate is a recent OWP characterized by a chemical composition rich in recalcitrant molecules and little is known about its impacts on dissolved fluxes in the scientific literature.

In order to evaluate the impacts of biogas digestate and winter crop on DOC and nitrates fluxes in soil, the experimental site EFELE from the SOERE PRO network (https://www6.inra.fr/valor-pro) was followed. The long-term evolution of the repeated application of OWP since 2012 was assessed for three different treatments: pig slurry, biogas digestate from the anaerobic digestion of pig slurry and a mineral fertilizer as a control. Lysimeters were monitored from 2014 to 2022 (8 drainage seasons) with two replicates per modality and depth (40 and 90 cm) under winter cover of wheat or mustard. The drainage seasons lasted from November to April. The DOC and nitrates dynamics observed for the four years under wheat and the four years under mustard were repeatable. Nitrates leaching losses were low under mustard (2.7 ± 2.3 kg N.ha-1 at 40cm and 0.9 ± 0.8 at 90cm), which had fulfilled its role as a catch crop, and higher under wheat (30.5 ± 12.9 kg N.ha-1 at 40cm and 14.3 ± 10.1 at 90cm), regardless of treatment. Regarding the DOC fluxes at 40cm depth, there was a significant difference between mustard (34.0 ± 11.4 kg C.ha-1) and wheat (20.6 ± 11.1 kg C.ha-1). DOC fluxes under biogas digestate were significantly higher (36.3 ± 16.2 kg C.ha-1) than under mineral fertilizer and pig slurry (21.4 ± 7.4 kg C.ha-1  on average). At the beginning of the drainage season, the DOC concentrations dynamics were already significantly different between digestate and the two other treatments under mustard, which was sown in September and already well developed. Under wheat, which was sown in November, there was no difference between treatments at the beginning of the season. It was only in the middle of winter, when the crop had more time to develop, that a difference could be observed. It seemed that the crop effect controlled the treatment effect. DOC fluxes to groundwater (90 cm) were not significantly different between treatments or crop (7.4 ± 6.0 kg C.ha-1 on average). Part of the C could be stored between 40cm and 90cm depth or mineralized.

How to cite: Didelot, A.-F., Jardé, E., Morvan, T., Gaillard, F., Liotaud, M., and Jaffrezic, A.: Effects of biogas digestate and winter crops on dissolved organic carbon and nitrates fluxes in soil., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12433, https://doi.org/10.5194/egusphere-egu23-12433, 2023.

vSSS.16
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EGU23-12784
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ECS
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Virtual presentation
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Can alternating groundwater level affect uncontrolled nitrogen losses from rewetted histosols under urea and CAN fertilization? Evidence from mesocosm lysimetric study on nitrogen atmospheric fluxes 
Sebastian Kuśmierz, Katarzyna Połeć, and Monika Skowrońska

The current scientific knowledge is insufficient enough to indicate universal agricultural strategies which could intensify crop production while lowering enivornemntal antrophogeinc impact from agricultural origins. Ongoing climate change forces farming adaptation, especially in water management at the field level. One of the most commonly used practices to counteract the evergrowing frequency of precipitation anomalies is to alter the groundwater table in agricultural areas. Still, the effects of this practice can lead to changes in oxygen conditions and bioactivity in the soil, which can have hard to predict consequences on nitrogen soil-atmosphere fluxes. We hypothesized that changes in aerobic conditions in the saturation zone and moisture content in the capillary zone can increase N2O emissions and lower NH3 volatilization from fertilized histosols under rewetting conditions. To test this hypothesis we ran a mesocosm study using small scale lysimeters with shifting water table. 6 different water table alternation strategies  were examined (permanent 0,1 m , 0,2 m, 0,3 m, 0,4 m, 0,5 m below surface + fluctuating 0,1 - 0,5 m below surface) in the confrontation with 100kg N/ha Urea and CAN fertilization treatments. Our research showed that permanently higher groundwater level lowers the time between nitrogen application and N2O emission peak but has no significant impact on the total N2O outflux, while fluctuation of the water table significantly increases N2O emissions from CAN treatment. None of the tested water table alternation strategies showed significant differentiation in NH3 volatilization. Hence, further investigation is still needed to reveal the complexity of soil water content impact on nitrogen turnover.

How to cite: Kuśmierz, S., Połeć, K., and Skowrońska, M.: Can alternating groundwater level affect uncontrolled nitrogen losses from rewetted histosols under urea and CAN fertilization? Evidence from mesocosm lysimetric study on nitrogen atmospheric fluxes, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12784, https://doi.org/10.5194/egusphere-egu23-12784, 2023.