We invite contributions from manipulative field experiments, observations in natural environmental gradients, and modeling studies that explore the environmental change impacts on plant-soil interactions, biogeochemical cycling of C, N, P, microbial diversity and decomposition processes, and deep-soil biogeochemistry. Submissions that adopt novel approaches, e.g. molecular, isotopic, or synthesize outputs from large-scale, field experiments focusing on plant-soil-microbe feedbacks to warming, wetting, drying and thawing are very welcome.
This is the continuation of our 2023 and 2024 successful session on the same topic and focus. We would like to continue bringing people together with this session in order to learn from each other’s studies on soils and environmental change from a global range of pedogenic and environmental settings.
Understanding the alterations in soil microbial communities in response to climate warming and their controls over soil carbon (C) processes is crucial for projecting permafrost C-climate feedback. However, previous studies have mainly focused on microorganism-mediated soil C release, and little is known about whether and how climate warming affects microbial anabolism and the subsequent C input in permafrost regions. Here, based on a more than half-decade of in situ warming experiment, we show that compared with ambient control, warming significantly reduces microbial C use efficiency and enhances microbial network complexity, which promotes soil heterotrophic respiration. Meanwhile, microbial necromass markedly accumulates under warming likely due to preferential microbial decomposition of plant-derived C, further leading to the increase in mineral-associated organic C. Altogether, these results demonstrate dual roles of microbes in affecting soil C release and stabilization, implying that permafrost C-climate feedback would weaken over time with dampened response of microbial respiration and increased proportion of stable C pool.
How to cite: Yang, Y., Qin, S., Zhang, D., and Wei, B.: Dual roles of microbes in mediating soil carbon dynamics in response to warming, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3006, https://doi.org/10.5194/egusphere-egu25-3006, 2025.
Global warming raises critical concerns about the redistribution of carbon from soil organic matter to the atmosphere, a process governed by mechanisms that remain poorly understood, making it difficult to predict the outcomes of climate change. Traditionally, warming was expected to increase CO₂ emissions from soils. However, a decade ago, this simplistic view was challenged by observations showing that these initially large emissions gradually diminish over time. This phenomenon represents an ecosystem feedback that has yet to be fully explained.
In this study, we combined laboratory experiments and modelling approaches at the Harvard Forest experiment to investigate the impact of a nine-year +5°C warming treatment on microbial functioning and associated soil carbon losses. Our findings reveal a nuanced interplay between direct and indirect effects of temperature, emphasizing the gradual optimization of microbial traits to warming as a key factor explaining the initially large soil carbon losses that are mitigated over time. These results bridge fundamental ecological principles with observed global change impacts, providing an explanation for the warming-induced carbon losses observed in soils worldwide.
How to cite: Brangarí, A. C., Knorr, M. A., Frey, S. D., and Rousk, J.: The gradual optimization of microbial traits regulates warming-induced carbon losses in soils, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2321, https://doi.org/10.5194/egusphere-egu25-2321, 2025.
Plant-microbe interactions control ecosystem functioning. Soil microbial communities regulate nutrient cycling, and by this influence plant productivity and community composition. Wetland plants steer the soil und rhizosphere microbiome through the release of organic compounds and oxygen from roots as well as through the input of litter.
The present study investigates warming effects on soil microbial community composition and activity in two Baltic salt-marsh sites with similar vegetation composition and soil characteristics in relation to plant community composition and soil redox conditions. We hypothesize that soil microbiomes from both sites show a similar response to warming through modulation in taxonomic composition and enzymatic activity.
Soil sods from salt marshes in Sweden and Denmark were transported to the Institute of Plant Science and Microbiology at the University of Hamburg and exposed to a large range of warming treatments in a state-of-the-art experimental facility with automated above and belowground heating (ambient, +3°C, +6°C) over two consecutive growing seasons. We analyzed 16S rDNA and ecoenzymatic activity across different soil depths to investigate the warming response of the microbial community.
In contrast to our hypothesis, a consistent response to warming was missing. Instead, we found that sample origin and soil depth had a strong effect on microbial community composition and ecoenzymatic activity. We observed a stronger warming effect on microbial community composition for samples originating from Denmark, which also showed a stronger differentiation across soil depth. Samples originating from Sweden showed less pronounced depth differentiation, and a weaker response to warming in microbial community composition. However, samples from Sweden had a higher variability of ecoenzymatic activity, suggesting a physiological adaptation to warming rather than an adaptation through changes in taxonomic composition as seen in samples from Denmark. In my presentation, I will further discuss potential effects of vegetation composition and productivity as well as biogeochemical parameters under warming on microbial community composition in salt marsh ecosystems.
How to cite: Schwarzer, J., Logemann, E., Mittmann-Goetsch, J., Jensen, K., Mueller, P., and Liebner, S.: Warming effects on soil microbial community composition in Nordic salt marsh ecosystems, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12761, https://doi.org/10.5194/egusphere-egu25-12761, 2025.
Understanding the moisture and temperature sensitivity of soil respiration is important as climate change brings more variation in soil moisture (e.g., drought, drying, and rewetting events) and soil temperature (e.g., warming). However, soil moisture and soil temperature sensitivity of soil respiration are often assumed fixed, neglecting environmental controls that might modulate them. Moreover, the soil moisture sensitivity is likely different during drying as opposed to rewetting periods due to the different processes involved, and soil temperature sensitivity is often estimated without separating the drying and rewetting periods, during which processes with contrasting temperature sensitivity are dominant. Here, we collected high-frequency field data on soil respiration, soil moisture, and soil temperature from COSORE (27 sites) and NEON (47 sites) and defined the moisture and temperature sensitivity of soil respiration in both the drying and rewetting periods. Using the monthly standardized precipitation evapotranspiration index (SPEI) and monthly temperature over the last 30 years of each site, we characterized the historical climate conditions by drought frequency and temperature amplitude. Then, the moisture and temperature sensitivity of soil respiration in both the drying and rewetting periods were explained by historical climate conditions, vegetation index, soil properties, and their interactions. The results will provide a better understanding of the environmental controls on soil moisture and temperature sensitivity of soil respiration.
How to cite: Li, X., Chakrawal, A., Hugelius, G., and Manzoni, S.: Environmental controls on the temperature and moisture sensitivity of soil respiration during drying and rewetting events , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8485, https://doi.org/10.5194/egusphere-egu25-8485, 2025.
Climate change rapidly alters the conditions which govern the differentiation of soils, with implications for the wide range of indispensable ecosystem functions that soils provide. The ability of soils to perform these functions in the future will depend on how quickly soil physicochemical and biotic properties respond to warming. On the one hand, soil development is a process that takes millennia. On the other hand, soil processes are mediated by chemical and microbial reactions that can be very rapid, potentially altering soil functioning over a period of months to years. In addition, soils are highly diverse depending on parent material and environmental conditions. As a result, simple questions about soil-climate responses remain unanswered: How long does it take for soil to acclimate to a changed climate? And do some soil properties acclimate faster than others?
Here, we addressed these questions with a novel approach which combines elevation gradients with soil transplantation experiments. Elevation gradients are used to study the potential long-term effects of climate, because they can control for parent material while allowing soils to acclimate to climate differences between elevations over long periods of time. Transplant experiments across elevation are warming experiments in which the elevational changes in climate across space are used to investigate short-term climatic responses. Based on the assumption of space-for-time, soils at low elevation can represent the expected state of transplanted soils that have fully acclimated to a new climate over longer timescales. Observations across different transplant experiments thereby provide the opportunity to see whether and how quickly short-term changes converge on expected longer-term changes. To this end, we collected topsoils from eleven elevational transplant experiments across the Alps, Scandinavia and the Rocky Mountains which varied in experiment duration between 1-9 years. We analyzed elevational differences and short-term warming-responses of organic matter dynamics (pools and fluxes), organic matter characteristics (e.g. fraction, functional groups, thermal stability), microbial communities (bacteria, fungi) and soil physicochemistry (pH, particle size, weathering products).
We found that short-term responses of soils to warming were mainly in the same direction as expected changes based on elevational differences between soils. Moreover, different types of soil properties acclimated at comparable and rapid paces: Organic matter dynamics had acclimated to warmer climate by up to 57% of expected change (16% on average across sites). Organic matter characteristics had acclimated by up to 74% (14% average), microbial communities by up to 82% (average 14%) and soil physicochemistry by up to 67% (23% average). Acclimation was significantly related to experiment duration for organic matter dynamics, microbial communities and soil physicochemistry. The observed relationships suggest that, with simplistic assumptions, soils would fully acclimate to the experimental climate change within two decades. Based on climate projections, we estimated that the experiments simulated an average cumulative warming of four to five decades. Taken together, we conclude that topsoil properties can respond rapidly to climate change, implying that many soil functions could keep up with climate change without major time lags.
How to cite: Wasner, D., Walker, T. W. N., Bektaş, B., Network, T., and Alexander, J. M.: Rapid acclimation of topsoil physicochemical and biotic properties to experimental climate change, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12202, https://doi.org/10.5194/egusphere-egu25-12202, 2025.
Ecosystem warming experiments offer key insights into the functioning of plants, microbes, and biogeochemical processes in a warmer world, but are limited by their ecological context, within site heterogeneity, and instrumentation. The Soil Warming Experiment to Depth Data Integration Effort (SWEDDIE) is a joint platform developed by the DeepSoil2100 network (23 warming experiments worldwide) to overcome these limitations through the creation of a network-wide database.
The SWEDDIE database is designed with FAIR principles to accommodate a wide range of data types, with a streamlined data ingestion system and user-friendly query and reporting tools. Comprehensive metadata reporting standards enable SWEDDIE to serve as a repository for past, present, and future datasets. Harmonization of data is facilitated with data dictionary files that accompany and describe variables in each data file and also store sensor and methods information. SWEDDIE consists of both publicly accessible and network-only data tiers, and is hosted on ESS-DIVE to leverage existing data repository infrastructure. Data ingestion, wrangling, and synthesis tools for SWEDDIE are also available in a companion R package.
A key tenet of SWEDDIE is the inclusion of soil measurements below 0.2 m, as the warming response of C stocks in deeper soil layers remains both highly uncertain and consequential for the global C cycle. Accordingly, we welcome new sites and data submissions, provided that > 1 °C warming has been observed below this depth. The first synthesis analysis with SWEDDIE focused on the impact of warming on soil moisture, while also serving to test the SWEDDIE data model and refine the harmonization approach. The results of this analysis provide quantitative evidence that warming leads to decreased soil moisture throughout the soil profile, but with more drying in surficial compared to deeper soil layers. The degree of warming correlates directly with the magnitude of soil drying, but the specific relationship between warming and drying varies by site as well as seasonally.
SWEDDIE is at its core a community project. The results of the preliminary soil moisture analysis are a key building block of one of the next planned synthesis efforts: using selected experiments to benchmark soil C warming responses with the ecosys model. This demonstrates the positive feedback inherent to this platform, i.e., that active community engagement leads to improved data coverage, which in turn enhances our capacity to generalize warming responses across ecological gradients, inform global models, and quantify potential experimental biases.
How to cite: Beem-Miller, J., Riley, W., Torn, M., Schmidt, M., and Reich, P.: A New Model for Synthesis: The Soil Warming Experiment to Depth Data Integration Effort (SWEDDIE), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-21285, https://doi.org/10.5194/egusphere-egu25-21285, 2025.
Empirical assessments are valuable sources of knowledge to evaluate impacts of global change on organisms and ecosystems. Experimental data are especially valuable as they offer controlled conditions for testing hypotheses and establishing process understanding. However, these approaches are also notoriously difficult to upscale to broad geographic extents as they require detailed and often labor-intensive studies in multiple field sites. Meta-analyses based on shared protocols and ‘distributed experiments’, that is, experiments replicated across broad geographic or environmental extents, offer opportunities to overcome these challenges. The International Tundra Experiment (ITEX) is one of the largest and longest-running distributed experiments in plant and ecosystem science. In this talk, we will present a recent ITEX data synthesis project that used experimental data to assess the processes underlying increased ecosystem respiration in the warming tundra.
Arctic and alpine tundra ecosystems are large reservoirs of organic carbon, and climate warming may stimulate ecosystem respiration and release carbon into the atmosphere. The magnitude and persistence of this stimulation and the environmental mechanisms that drive its variation remain uncertain. To address this knowledge gap, we synthesized 136 datasets from 56 open-top chamber in situ warming experiments located at 28 arctic and alpine tundra ITEX sites that have been running for up to 25 years. We show that a mean rise of 1.4 °C in air and 0.4 °C in soil temperature results in an increase in growing season ecosystem respiration by 30%, due to increases in both plant-related and microbial respiration. There was substantial variation in the warming effects on respiration, however. Such context-dependencies have often frustrated attempts at generalizations in ecology, but we show how the distributed experimental approach allowed us to disentangle the ecological processes underlying these variations. We found that tundra sites with stronger nitrogen limitation, and sites in which warming stimulated plant and microbial nutrient turnover, seemed particularly sensitive in their respiration response to warming. This knowledge may improve the accuracy of global land carbon–climate feedback projections. Our study highlights how empirical approaches that enable process understanding of context-dependent ecological variation may allow generalization and prediction of complex ecological phenomena.
How to cite: Vandvik, V. and Maes, S. and the coauthors: On how a distributed experimental approach informs our understanding of the processes underlying context-dependencies in the ecosystem respiration response to a warming tundra, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-21337, https://doi.org/10.5194/egusphere-egu25-21337, 2025.
Freeze-thaw events disrupt soil pore structure, with implications for larger scale greenhouse gas fluxes and nutrient balance in winter and the growing season. Given its strong influence on soil C and N cycling, we need a better understanding of how pore structure is altered by freeze-thaw disturbances. Our objective was to investigate and quantify changes in the physical structure of soil, in response to experimental freeze-thaw disturbance.
We collected intact soil cores from a northern hardwood forest in New Hampshire, USA. The soils were held at two contrasting water contents (low vs. high moisture) and then subjected to repeated freeze-thaw cycles in the laboratory, alternating between -10 °C and +4 °C. Soil porosity and pore network connectivity were determined during each freeze and thaw event using X-ray computed tomography (XCT) imaging. CO2 fluxes were measured continuously to track changes in microbial respiration following each disturbance. In addition, soil organic carbon was characterized using high resolution FTICR-MS to determine changes in the available C pool. This work links physical changes in soil structure to biogeochemical responses, highlighting the role of microsite scale processes on core-scale fluxes.
How to cite: Patel, K., Contosta, A., Petersen, W., Teixeira, C., Varga, T., and Zheng, J.: Understanding soil pore response to winter freeze-thaw, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14297, https://doi.org/10.5194/egusphere-egu25-14297, 2025.
Microbial biomass and nutrient content in soils are crucial indicators of ecosystem health and soil productivity as they reflect intricate relationship among soil organic matter decomposition, nutrient cycling, and resource availability for plants and soil organisms. In the treeline ecotone of Nepal Himalaya regions, there has only been a limited research focus on belowground microbial biomass and how it varies in treeline ecotones of near-natural forest ecosystems, particularly in the context of climate change and dynamic treeline positions. With this research, we tried to fill this research gap by measuring soil microbial biomass carbon (MBC), nitrogen (MBN) and phosphorus (MBP) along transects with elevational vegetational zones to assess the nutrient limitation in the forefront of the forest ecotone region. The main objective of our study is to disentangle the relationship between the soil microbiome and nutrient limitation as a controlling factor of tree growth.
We collected 118 soil samples from two slope sectors (northeast and northwest) each with four elevational vegetational zones (3910 to 4260 meter above mean sea level) upper dwarf shrub heath: UD, lower dwarf shrub heath: LD, upper krummholz: UC, lower krummholz: LC. Each zone consisted of four 20x20 m² plots, from which composite samples representing soil horizons were taken. MBC and MBN were measured using fumigation-extraction methods. For MBP, after fumigation-extraction, we slightly modified the quantifying method using Inductively Coupled Plasma - Optical Emission Spectroscopy (ICP-OES).
Our result showed low microbial biomass content in soils of the treeline ecotone indicating nutrient limitation which might influence the growth patterns of vegetation and ecosystem dynamics in the alpine treeline of Himalaya. Specifically, there was a significant decline in MBC values with increasing soil depth, (p-value ≈ 0), with the highest mean MBC of 561 µg g-1 dry soil in the O-horizon followed by progressively lower values in the Ah-horizon: 277 µg g-1, E-horizon: 112 µg g-1 and Bh-horizon: 56.9 µg g-1. Similar decreasing trends were observed for mean MBN and MBP. Elevational zone wise variation followed the order of LD > UD> LC> UC for mean MBC and LD>UD>LC>UC for mean MBN. Unlike MBC and MBN, MBP showed significant differences (p-value= 0.011) among four elevational zones and in the decreasing order of LC > UD > LD > UC with mean MBP values of 184 µg g⁻¹, 106 µg g⁻¹, 90 µg g⁻¹ and 86.8 µg g⁻¹ dry soil, respectively. The ratio of MBC and MBN in the UD elevational zone was high, which might be related to the very low MBN content in the soils. MBC and MBN had a strong positive correlation (r = 0.85). Higher microbial biomass values in the higher altitude zones LD and UD than in LC and UC indicate an active microbial pool in open (higher amount of sun radiation) and dwarf shrub vegetation zone compared to closed canopy in the Rhododendron campanulatum krummholz zone. These findings contribute to a better understanding of nutrient limitations and their role in treeline shift dynamics within the krummholz dominated upper treeline ecotone in the study area.
How to cite: Adhikari, R., Böhner, J., Chaudhary, R. P., Gall, C., Huber, J., Maharjan, A., Oelmann, Y., Parajuli, M., Schickhoff, U., Seitz, S., Subedi, C. K., and Scholten, T.: Soil microbial biomass and nutrient limitation in high altitude treeline ecotones of central Nepal Himalaya, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-253, https://doi.org/10.5194/egusphere-egu25-253, 2025.
Rapid expansion of deciduous shrubs and evergreen trees on the Arctic tundra could induce large losses of soil carbon stocks through increased rhizosphere priming. Through the use of isotopic and molecular techniques, we investigated whether the belowground carbon cycling differed between three plant species that are encroaching Canadian tundra. 13CO2 pulse chase labelling showed that dwarf shrubs (Betula glandulosa) had faster turnover of recent 13C-photosynthates belowground than tall shrubs (Alnus viridis) and black spruces (Picea Mariana). Depth-resolved 13C flux estimations and partial 13C source isolation, both from field and lab measurements, elucidated multiple drivers of the differences in belowground carbon cycling. Turnover rates were strongly dependent on relative belowground carbon allocation, source of respiration and soil depth. Carbon cycling data will be compared with microbial community composition in bulk and rhizosphere soil to disentangle the specific interactions between encroaching plants and their soils. Overall, both plant and soil characteristics were key influences on the fate of recently assimilated carbon belowground. Our work suggests that changing plant communities will influence the belowground carbon cycling of the Arctic tundra. Our data pinpoints towards multiple factors influencing the feedback from northern ecosystems to on-going climate change, which further complicates accurate predictions of soil carbon losses in the northern hemisphere.
How to cite: Rijkers, R., Wegner, R., Sauerland, L., Frey, L., and Wild, B.: Shrub and tree encroachment alter plant-soil interactions in low Canadian Arctic, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4047, https://doi.org/10.5194/egusphere-egu25-4047, 2025.
Posters on site: Mon, 28 Apr, 08:30–10:15 | Hall X1
Permafrost underlies 25% of the land surface area of the northern hemisphere and stores approximately a third of the world's organic soil carbon (C). When permafrost thaws, organic C that was frozen in a suspended state of decomposition rejoins the active layer and can be respired by microbial organisms within the soil as CO2 or CH4. As climate warming advances, permafrost thaw is likely to occur more within abrupt (seasons to decades) timelines as opposed to the generally better understood gradual thaw timelines (decades to centuries). Abrupt timelines increase C emissions over a shorter time scale. This increase in C respiration can be further spurred by the reintroduction of nutrients that were frozen in the permafrost, alongside the soil C. In this study, 1m intact soil cores were collected from a palsa in Northern Finland, and incubated in ex-situ mesocosms for 12 weeks with continuous GHG production measurements. In tandem, subsamples of the soil cores were collected pre- and post- simulated abrupt and gradual thaw scenarios for metagenomic analysis. The coupling of these methods revealed a significant increase of GHG production in the abrupt thaw simulation, as measured by the mesocosm incubations. In the permafrost horizon, this was coupled with a shift to an increase of activity of the intermediate C cycle steps leading to respiration. Additionally, a large taxonomic shift was observed in the permafrost microbial community structure when comparing samples before and after the thaw simulations. Gene abundances associated with nitrogen cycling increased in the abrupt thaw simulation, while there was little discernible change in the Fe and S cycling dynamics pre- and post- thaw. This multidisciplinary approach lays groundwork for our evolving understanding of abrupt permafrost thaw and emphasizes the differences in C cycling strategies microbial communities utilize in abrupt and gradual thaw timescales.
How to cite: Baysinger, M., Laurent, M., Liebner, S., Bartholomäus, A., and Treat, C.: Abrupt thaw processes linked to enhanced intermediate C cycle steps within palsa soil mesocosms: a metagenomic analysis, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8740, https://doi.org/10.5194/egusphere-egu25-8740, 2025.
Tundra ecosystems are vast reservoirs of organic carbon and sensitive areas to climate change. The plant community and soil properties in tundra are changing significantly due to climate warming, which may further affect the temperature sensitivity of soil organic carbon (SOC) decomposition. However, the microbial mechanism by which plant-derived C input affects the temperature sensitivity of SOC decomposition remains unclear. Here we used quantitative stable isotope probing of DNA to examine how bacterial taxa affect the temperature sensitivity of SOC decomposition in an alpine tundra following the addition of glucose. Our results showed that the glucose addition caused significant changes in microbial community composition, with microorganisms transitioning from the sensitive taxa at lower temperatures (5-15℃) to the sensitive taxa at higher temperatures (15-25℃), which may explain why the Q10 of native SOC decomposition increased in 15-25 ℃, compared with no glucose addition. The study suggests many bacterial taxa change with temperature and plant-derived C input, and community-assembled traits of microbial taxa may better predict SOC dynamics in the alpine tundra.
How to cite: Chang, Q., Guo, Z., He, Y., and Bai, E.: Plant-derived C input regulates the temperature sensitivity of soil organic carbon by changes in bacterial community composition in an alpine tundra, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9675, https://doi.org/10.5194/egusphere-egu25-9675, 2025.
Temperature sensitivity (Q10) of soil organic matter (SOM) decomposition is a crucial parameter to predict soil carbon (C) dynamics and its feedback to climate change. Soil management affects aggregate formation and decomposition, where the impact on Q10 of SOM decomposition within aggregates remains unknown. Using a 14-year field experiment, we demonstrate that maize straw-amended soil had lower SOM stability and higher Q10 than biochar-amended soil, with aggregate size playing a central role in response to the management. Biochar-derived stable compounds accumulate in small macroaggregates (SMA) and microaggregates (MA), as indicated by the increased benzene polycarboxylic acids and decreased 14C age and δ13C. Besides, biochar facilitated C sequestration by increasing mineral protection, microbial C use efficiency, and microbial necromass C accumulation in these smaller aggregates, while large macroaggregates (LMA) were less effective to sequester SOM (high Q10) than smaller aggregate sizes. Maize straw primarily sequestered soil C through SMA by raising mineral protection and decreasing microbial C decomposition. However, it was less effective than biochar in soil C sequestration due to the greater susceptibility of maize straw-derived C to decomposition under warming conditions (high Q10). As such, soil management practices mediate the stability and Q10 of SOM through specific aggregate sizes. Our findings contribute to a better understanding of the impact of aggregate sizes on the carbon-climate feedback in agriculture.
How to cite: Chen, Y. and Sun, K.: Aggregate size mediates temperature sensitivity of soil organic matter decomposition in response to soil management, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2684, https://doi.org/10.5194/egusphere-egu25-2684, 2025.
The subalpine ecosystems of the Bieszczady Mountains are characterized by a mosaic of blueberry shrubs (Vaccinium myrtillus) and tall-grass vegetation, with significant implications for soil organic matter (SOM) dynamics. This study explores how vegetation type influences the content and spectroscopic properties of water-extractable organic matter (WEOM) in the topsoil horizons (O and A) in this region. WEOM is a crucial, bioavailable component of SOM that plays a significant role in nutrient cycling and carbon sequestration, particularly in sensitive mountain ecosystems.
Samples of topsoil horizons (O and A) were collected from 20 sites dominated by blueberry shrubs or tall-grass vegetation. Water extracts were analyzed to determine WEOC and WETN concentrations using TOC analyzers. The chemical properties of WEOM were characterized via FTIR-ATR spectroscopy and UV-Vis spectrophotometry. Specific ultraviolet absorbance (SUVA254) and absorbance ratios (E2/E4, E2/E6, and E4/E6) were calculated to assess the aromaticity and molecular composition of WEOM.
The O horizons of soils under blueberry shrubs exhibited significantly higher WEOC concentrations compared to those under tall-grass vegetation. However, WETN concentrations were not significantly different between vegetation types. The WEOC/WETN ratio was higher in soils under blueberry shrubs, indicating more carbon-rich WEOM in these areas.
Spectroscopic analyses revealed notable differences in WEOM composition. FTIR spectra showed more pronounced bands associated with aliphatic compounds and carboxylic groups in WEOM from shrub-dominated soils, suggesting a higher proportion of less decomposed organic matter. UV-Vis spectroscopy indicated higher SUVA254 values for WEOM in grass-dominated soils, reflecting greater aromaticity and advanced decomposition. In the A horizons, differences in WEOC and WETN concentrations and WEOM properties were minimal, likely due to microbial homogenization and reduced vegetation influence.
The results highlight how vegetation significantly affects WEOM quantity and quality, especially in the organic-rich O horizons. Soils under blueberry plants exhibit higher WEOC concentrations and carbon-dominated WEOM, which may improve carbon retention and slow decomposition rates. In contrast, tall-grass vegetation helps to produce more aromatic WEOM, indicative of advanced microbial processing. These findings suggest that shrubification, driven by climate change, can influence WEOM composition and stocks, with implications for carbon cycling and nutrient dynamics in subalpine ecosystems.
This study emphasizes the importance of vegetation type as a key determinant of WEOM properties, shaping both the storage and bioavailability of nutrients in mountain soils. These insights are essential for effective vegetation management and the preservation of ecological functions in fragile subalpine zones.
How to cite: Kramarczuk, P.: Influence of vegetation on the quantity and quality of water-extractable organic matter in the subalpine zone of the Bieszczady Mountains (Eastern Carpathians)., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3150, https://doi.org/10.5194/egusphere-egu25-3150, 2025.
Soil organic carbon (SOC) stock is the largest terrestrial carbon reservoir, with a substantial portion stored in the subsoil below 20 cm. The near-synchronous warming of the subsurface poses a threat to SOC storage across the whole soil profile. However, whether topsoil or subsoil is more vulnerable to warming still remains highly debated. Here, we utilize 213 matched observations from 60 field experiments to compare the responses of SOC stock to warming across depth. We find that warming causes SOC losses both in topsoil and subsoil. Moreover, multiple lines of evidence indicate no significant difference in SOC responses to warming at different soil depths, suggesting a consistent SOC loss rate throughout the whole soil profile. Despite the consistent loss rate, subsoil below 20 cm is projected to contribute over 60% absolute SOC losses across the 0-100 cm soil profile under the shared socioeconomic pathways 5-8.5 scenario due to its large SOC stock. We show that SOC in subsoil is as susceptible to warming-induced loss as in topsoil. Neglecting subsoil carbon loss will significantly underestimate the positive climate-carbon cycle feedback.
How to cite: Wu, W. and Zhu, B.: Consistent soil organic carbon loss rate across depth under warming, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7845, https://doi.org/10.5194/egusphere-egu25-7845, 2025.
Soils are a major carbon (C) reservoir, with subsoils (>20 cm) storing the majority of this C. Predicting the response of subsoil C to global change remains a critical research priority, yet long-term field observations for forest ecosystems are scarce. In this study, we assess temporal C dynamics in mineral soils to 90 cm depth of 62 temperate European beech (Fagus sylvatica) stands in Austria using data from sampling campaigns in 1984, 2012 and 2022. Our results show a significant increase in C stocks between 0-20 cm and a significant decrease in C stocks between 20-50 cm and 50-90 cm depth, suggesting substantial C losses from the subsoil. These losses outweighed the C gain in topsoils, resulting in an overall soil C loss since the 1980s. Organic-rich calcareous soils appear to be particularly vulnerable to C loss, probably because they are less effective at stabilising C than soils on other substrates. We suggest that changes in climate (i.e. warmer and wetter) and factors such as changes in rooting depth or litter inputs may underlie the observed patterns of depth-dependent soil C changes. The estimated soil C loss accounted for 23% of the C accumulated in aboveground biomass, as determined by dendrochronological analysis, indicating a reduction in the ecosystem's carbon sink capacity. Our results highlight the importance of including subsoil C in forest ecosystem assessments, as it plays a key role in the overall carbon balance.
How to cite: Mayer, M., Dolschak, K., Winter-Artusio, E., Grabner, M., Tatzber, M., Ahmed, I. U., Wächter, E., Berger, I. K., Berger, P., Wanek, W., and Berger, T. W.: Substantial subsoil carbon loss from beech forests since the 1980s, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16954, https://doi.org/10.5194/egusphere-egu25-16954, 2025.
Global warming will lead to a temperature rise of the soil, with a stronger effect in high latitude areas as compared to the global average. Soil warming could cause positive carbon-climate feedback, but this is still subject to many uncertainties. To enhance the understanding of how warming impacts underlying biogeochemical processes in top – and subsoils, our study makes use of a century-scale geothermal warming gradient. It is located in an aspen-dominated subarctic forest in the southern Yukon-Territory, Canada. A previous study at the site showed the SOC-stock to be reduced with warming, while the N-stock remained mainly unchanged. Thus, the C:N ratio was reduced, which was particularly pronounced in subsoils. Moreover, N shifted from the particulate-organic matter (POM) pool to the mineral-associated organic matter (MAOM) pool. We hypothesize the shift to be related to a higher microbial contribution to the MAOM fraction. In addition, the contribution of plant-derived OM in the subsoil might have decreased. This might be due to a change of root biomass distribution along the soil profile, as it is assumed that warming enhances N availability and the distribution of soil moisture. Furthermore, we hypothesize the soil structure to be a relevant factor for the distribution and loss of SOC, as the fraction of sand and stable aggregates (S+A) might be reduced with warming.
To understand the coupling- or decoupling of C- and N cycles, we will determine biogeochemical parameters at four warming intensities up to a warming of +10 °C to a depth of 80 cm. This design allows us to identify potential non-linear responses and it includes different warming scenarios. We will measure C- and N stocks of the POM, S+A and MAOM fraction. To moreover address the warming effect on the relative organic matter turnover, δ13C and δ15N values will be analyzed. For soil structural changes, the mean weight diameter of water-stable aggregates is evaluated. Furthermore, the coarse- and fine root biomass is assessed along the soil profiles. This comprehensive study will gain valuable biogeochemical insights and first results of ongoing evaluations will be presented.
How to cite: Kehr, J., Peter, A., Finn, D., Tebbe, C., and Poeplau, C.: Soil organic matter dynamics along a long-term soil warming gradient in a subarctic forested ecosystem, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11489, https://doi.org/10.5194/egusphere-egu25-11489, 2025.
One of the most important questions of our time is how ecosystems will be transformed by climate change. Here, we used a five-year field experiment to investigate the effects of climate warming on the cover and function of a sub-Arctic alpine ecosystem in the highlands of Iceland dominated by biological soil crust (biocrust), mosses and vascular plants. We used Open Top Chambers (OTCs) to simulate warming; standard surface and Normalised Difference Vegetation Index (NDVI) analyses to measure plant cover and function; gas analyzers to monitor biocrust respiration; and the Tea Bag Index approach to estimate mass loss, decomposition and soil carbon stabilization rates. Contrary to our initial hypothesis of warming accelerating an ecological succession of plants growing on biocrust, we observed a warming-induced decreased abundance of vascular plants and mosses —possibly caused by high temperature summer peaks that resemble heat waves— and an increase in the cover of biocrust. The functional responses of biocrust to warming, including increased litter mass loss and respiration rates and a lower soil carbon stabilization rates, may suggest climate-driven depletion of soil nutrients in the future. It remains to be studied how the effects of warming on biocrusts from high northern regions could interact with other drivers of ecosystem change, such as grazing; and if in the long-term global change could favor the growth of vascular plants on biocrust in the highlands of Iceland and similar ecosystems. For the moment, our experiment points to a warming-induced increase in the cover and activity of biocrust.
How to cite: Salazar, A., Gunnlaugsdóttir, E., Jónsdóttir, I., Klupar, I., Wandji, R.-P., Arnalds, Ó., and Andrésson, Ó.: Increased biocrust cover and activity in the highlands of Iceland after five growing seasons of experimental warming, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2609, https://doi.org/10.5194/egusphere-egu25-2609, 2025.
The quick accumulation of bioavailable phosphorus (bio-P) promoted the ecosystem development at the very beginning of pedogenesis on the Hailuogou Glacier foreland. It is still unclear what role and how microbe played in bio-P accumulation at the very beginning of pedogenesis. Using the Hailuogou Glacier foreland on Gongga Mountain as a natural laboratory, microbial community assembly, co-occurrence networks, and PCGs were examined across four successional stages (S1-S4) before the pioneer plant emerged. The results indicated that bacteria were the dominant domain in all four stages. At the very beginning of pedogenesis, microorganisms adapted to scare bio-P conditions by regulating the functional expression of key PCGs. Key genes, including pqqE, gcd, phoD, and 3-Phytase, played a crucial role in mineral phosphorus solubilizing and organic phosphorus mineralizing. Community assembly was predominantly driven by deterministic processes under environmental pressures. Tight cooperative network structures within the microbial communities and dominant microbial taxa were the major factors accelerating the bio-P releasing into the soil. It can be concluded that microbepromoted bio-P accumulation at the very beginning of pedogenesis by regulating PCGs and typical microbial community constructing. These findings provided new insights into the mechanisms by which microbial communities regulate phosphorus dynamics during pedogenesis process.
How to cite: Wu, Y., Xu, M., Bing, H., Zhu, H., Luo, C., and He, J.: Microbe promotes soil phosphorus bioavailability at the beginning of pedogenesis, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6318, https://doi.org/10.5194/egusphere-egu25-6318, 2025.
Climate change introduces significant uncertainty when assessing the risk of soil salinity in water-scarce regions. We combine a soil–water-salinity–sodicity model (SOTE) and a weather generator model (AWE-GEN) to develop a framework for studying salinity and sodicity dynamics under changing climate definitions. Using California’s San Joaquin Valley as a case study, we perform first-order sensitivity analyses for the effect of changing evapotranspiration (ET) rates, length of the rain season, and magnitude of extreme rainfall events. Higher aridity, through increased ET, shorter rainy seasons, or decreased magnitude of extreme rainfall events, drives higher salinity — with rising ET leading to the highest salinity levels. Increased ET leads to lower levels of soil hydraulic conductivity, while the opposite effect is observed when the rainfall season length is shortened and extreme rainfall events become less intense. Higher ET leads to greater unpredictability in the soil response, with the overall risk of high salinity and soil degradation increasing with ET. While the exact nature of future climate changes remains unknown, the results show a serious increase in salinity hazard for climate changes within the expected range of possibilities. The presented results are relevant for many other salt-affected regions, especially those characterized by intermittent wet–dry seasons. While the San Joaquin Valley is in a comparatively strong position to adapt to heightened salinity, other regions may struggle to maintain high food production levels under hotter and drier conditions.
How to cite: Mau, Y., Kramer, I., and Peleg, N.: Climate change shifts risk of soil salinity and land degradation in water-scarce regions, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6436, https://doi.org/10.5194/egusphere-egu25-6436, 2025.
Global temperatures could increase by approximately 4°C until 2100, according to IPCC climate scenarios, causing surface and subsoil will warm in synchrony with the atmosphere. This warming is predicted to accelerate soil carbon loss and greenhouse gas release, but also change the composition of soil organic matter in ways that affect its cycling and future vulnerability. This is important because despite low carbon concentrations, subsoils store more than half of the total global soil organic carbon. However, it remains largely unknown how this deep soil carbon will respond to warming. In this study we explore how 10 years of experimental field warming affects soil carbon quantity and quality in bulk soil and in functional (density) fractions in whole soil profiles.
After 10 years of experimental field warming of a temperate forest (Blodgett, Sierra Nevada, CA, USA), we analyzed carbon composition of bulk soil and density fractions using Diffuse Reflectance Infrared Fourier Transform spectroscopy. Soil carbon functional pools included free and occluded particulate organic matter (fPOM, oPOM) as well as mineral associated organic matter (MAOM), at 3 different depths (10-20, 40-50, and 80-90 cm). The results showed that the relative proportion of carbon in fPOM and oPOM decreased with depth and was lower in warmed plots. Soil carbon (C) quality in fPOM and oPOM did not change with warming or depth. However, C quality in MAOM was different, with 11% more aliphatic C in the topsoil (10-20 cm), and 17% more aromatic C in the deep soil (80-90 cm). This indicated an increasing level of SOC decomposition in subsoil >50 cm. With warming, most of the remaining organic matter in the deep soil was protected by mineral association, with relatively more aromatic C present. This raises the possibility that SOC that is mineral-associated in subsoil, especially in the form of aromatic C, might resist future warming more than SOC in other functional fractions.
How to cite: Sun, B., Rowley, M., Wiesenberg, G., Pegoraro, E., Torn, M., and Schmidt, M.: Organic matter in density fractions responds to 10 years of experimental field warming in a temperate forest, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6862, https://doi.org/10.5194/egusphere-egu25-6862, 2025.
Microbial carbon use efficiency (CUE) and nitrogen use efficiency (NUE) are key parameters determining the fate of C in soils. However, the paucity of investigations of microbial CUE and NUE dynamics through the soil profile with warming makes it challenging to evaluate the terrestrial C feedback to climate change. Here, based on soil samples from a whole-soil-profile warming experiment (0–1 m, +4 °C) and stable isotope (18O and 15N) tracing approaches, we examined the vertical variation of microbial CUE and NUE and its response to ~3.3-year experimental warming in an alpine grassland on the Qinghai-Tibetan Plateau. Our findings revealed that microbial CUE and NUE decreased along soil depth, a trend that was primarily controlled by soil C availability. We also observed differential warming effects on microbial CUE and NUE. Microbial CUE showed no significant response to warming in either the topsoil or deep soil. However, microbial NUE in the deep soil decreased by 53% under warming compared to non-warmed controls, suggesting that warming drives soil microbes to incorporate less N into their biomass in the topsoil. The decrease in microbial NUE was likely triggered by a reduction in soil N availability in the topsoil. Collectively, our work emphasizes the regulatory role of substrate availability on microbial CUE and NUE.
How to cite: Zhang, Q.: Effects of whole-profile warming on microbial carbon and nitrogen use efficiency at different soil depths in an alpine meadow, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7534, https://doi.org/10.5194/egusphere-egu25-7534, 2025.
Numerous studies have explored the impacts of nitrogen (N) deposition on soil organic carbon (SOC) dynamics. However, limited research has investigated the modulatory role of N deposition in urban to rural forests and the underlying microbial mechanisms. We carried out a 5-year field study to explore the links between microbial properties (microbial biomass carbon (MBC), microbial diversity, community composition and functions) and the different SOC fractions (particulate organic carbon, POC and mineral-associated organic carbon, MAOC) submitted to three levels of N addition rates (0, 50, and 100 kg N ha-1 yr-1) in urban–rural gradient forests in eastern China.
We discovered that N addition raised the soil ammonium nitrogen concentration in urban and suburban forests. However, it had no effect on soil acidification or POC or SOC accumulation，and in urban forest the stability was due to the 105 % to 110 % increase in the mineral-associated organic carbon (MAOC) through enhancing peroxidase activity and microbial biomass carbon. On the contrary, high nitrogen input significantly reduced SOC stability in the suburban and rural forest stands. High nitrogen input contributed to the loss of MAOC (-33.6 %) in the suburban forest stand due to the enhancement of microbial biomass nitrogen. High nitrogen addition also decreased the ratio of MAOC to SOC in the rural forest stand by 29.8 % through indirect pathways mediated by the soil Ca2+ concentration and polyphenol oxidase activity. We concluded that SOC in the urban forest was stable when subjected to increased nitrogen deposition, primarily due to the enhancement of MAOC driven by microbial function. This finding has contributed to a better understanding in predicting forest carbon cycling under conditions of global climate change and urban expansion.
How to cite: Tao, X. and Qian, Z.: Diverging patterns at urban-rural forest gradients: soil organic carbon stability responses to nitrogen addition, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7946, https://doi.org/10.5194/egusphere-egu25-7946, 2025.
The availability of phosphorus (P) in soils will ultimately determine forest productivity because of increasing P limitation in terrestrial ecosystems. However, how root exudates affect the availability of soil P in subalpine forests remains unclear. Here, bulk soils (BS) and rhizosphere soils (RS) under Abies fabri and Rhododendron decorum were respectively collected in the early-, mid- and late-growing seasons in a subalpine forest of eastern Tibetan Plateau, and low molecular weight organic acids (LMWOAs), microbial biomass P and P fractions were analyzed to decipher the effects of the plants on soil P availability. The P fractions in both BS and RS showed a distinct difference between A. fabri and R. decorum because of their different P acquisition strategies. The ericoid mycorrhiza-associated R. decorum sequestered soil available P through organic P mineralization, while the ectomycorrhizal mycorrhiza-associated A. fabri directly or indirectly acquired both the organic and inorganic P pools. Seasonal variations in soil available P further revealed that the difference in the P acquisition by the two species was closely associated with their growing stages. The increase in the concentrations of available P in RS of A. fabri was significantly related to the LMWOAs that dominated by citric acid, likely through the desorption or ligand exchange rather than acidification effect because of limited range of soil pH in the mid-growing season, while organic P mineralization contributed to available P for R. decorum in the early-growing season. The results of this study indicate that LMWOAs can significantly promote P availability in RS of A. fabri, mycorrhizal types and plant growing stages drive plant P acquisition, which results in the coexistence patterns of different species in the same habitat.
How to cite: Zhu, H., Wu, Y., and Bing, H.: Species-dependent phosphorus acquisition strategy modulates soil phosphorus cycle in the subalpine forest of eastern Tibetan Plateau, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9014, https://doi.org/10.5194/egusphere-egu25-9014, 2025.
Soil organic carbon (SOC) changes resulting from forestation (including afforestation and reforestation) play a crucial role in evaluating the forest-pathway contribution to global climate change mitigation within the framework of nature-based climate solutions. However, forestation may fail to increase SOC and even lead to SOC decline over certain time periods, potentially offsetting the climate mitigation benefits achieved through biomass carbon sequestration. To address this, we review global studies on forestation, encompassing both plantations and natural regeneration, and analyze the factors driving SOC changes after afforestation and reforestation. Our analysis reveals that higher initial SOC tends to cause regional soil carbon loss, with topography, climate, soil condition, and land use history together determining overall SOC changes after forestation. Furthermore, we utilize random forest models to predict future SOC dynamics following forestation, with significant variability observed across climate zones in first 30 years, and the contribution of SOC to total carbon sequestration appears lower than previously estimated. These findings highlight the need for greater consideration of local conditions when designing forestation strategies to optimize ecosystem carbon sequestration, and to enhance soil’s role in achieving sustainable climate change mitigation goals.
How to cite: Wang, Y., Xu, Y., Zhu, Y., and Qin, Z.: Global soil organic carbon changes with reforestation/afforestation, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9635, https://doi.org/10.5194/egusphere-egu25-9635, 2025.
Deadwood is an essential component of intact forest ecosystems. It is a hotspot of biodiversity, can contribute to water retention and has complex effects on various soil functions, such as the quality and quantity of soil organic matter. Whether deadwood makes a positive contribution to carbon storage in forest soils, and how site-specific parameters might contribute, has not been extensively investigated. We therefore ask how the effect of deadwood on the formation and stabilisation of soil organic matter varies with soil moisture.
The study was carried out as part of the BENEATH project in a near-natural beech forest in the Dübener Heide near Leipzig, Germany. Three monitoring sites (wet, intermediate, dry) were established on the slope of an old moraine along a natural soil moisture gradient. At all sites, undisturbed soil samples were taken at three depths (0-10 cm, 10-20 cm, 20-30 cm) directly under deadwood in an advanced stage of decay, as well as reference samples (at a distance of 2 m from the deadwood). Soil solution was collected under deadwood and on reference plots using suction plates and cups at 5 cm and 20 cm depth, respectively. Carbon (C) and nitrogen contents were determined for all samples. For soil samples, the size of differently stabilised C pools was determined by density fractionation. Soil respiration was measured monthly by chamber measurement on deadwood-influenced soil and on reference plots. Volumetric soil water content and soil temperature were continuously recorded using SMT100 sensors.
The highest soil organic carbon (SOC) contents and the greatest changes due to deadwood were found between 0 and 10 cm depth. At the wet and dry sites, deadwood had a positive effect on SOC content, at the intermediate site the effect was negative. SOC stabilisation was not affected. The concentration of dissolved organic carbon (DOC) in the soil solution was higher under highly decomposed deadwood than at the reference sites. Overall, the highest values were measured on the wet site. Soil respiration was increased on both wet and dry site under the influence of deadwood compared to the reference. The results indicate that the effect of deadwood on C dynamics is critically dependent on soil moisture. The influence of the deadwood itself on the soil water balance seems to be of particular importance. It is likely that changes in soil moisture (due to deadwood or soil properties) will lead to changes in microbial activity with effects on the intensity of processes such as microbial decomposition of SOC or release of organic C from deadwood or litter.
Our investigations should contribute to a better understanding of the role of deadwood in the C-cycle of forest soils. They can provide information for a more accurate accounting of C fluxes in forests and for a more climate-smart forest management.
How to cite: Schäfferling, R., Zeidler, E., Azekenova, A., Fontenla-Razzetto, G., Koller, A., Wordell-Dietrich, P., Zeh, L., Kniesel, B., Julich, S., Stutz, K., Feger, K.-H., Kalbitz, K., and von Oheimb, G.: The influence of deadwood on the carbon dynamics of a near-natural beech forest - a question of soil moisture?, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10174, https://doi.org/10.5194/egusphere-egu25-10174, 2025.
Posters virtual: Wed, 30 Apr, 14:00–15:45 | vPoster spot A
EGU25-1026 | ECS | Posters virtual | VPS4
Meta-analysis of direct nitrous oxide emissions and ammonia volatilization from irrigated wheat in calcareous soils under semi-arid conditionsWed, 30 Apr, 14:00–15:45 (CEST) | vPA.17
Nitrous oxide (N2O) is the most important stratospheric ozone-depleting gas of the 21st century. Most N2O emissions occur in soils and are associated with agricultural activities. Ammonia (NH3) is not a greenhouse gas, but it can indirectly contribute to greenhouse gas emissions. NH3 volatilization is an important indirect N2O emission pathway in agricultural systems. In addition, NH3 can have significant effects on both human health and the natural environment, and its emissions negatively affect biodiversity. A meta-analysis was conducted to evaluate NH3 and N2O losses and the effectiveness of adding urease and nitrification inhibitors on direct N2O emissions and NH3 volatilization. Data were used from 14 separate studies that simultaneously investigated direct N2O emissions and NH3 volatilization from irrigated wheat. All studies were conducted on irrigated wheat in semi-arid climates and on calcareous soils with urea application. The average direct N₂O emission factor for irrigated wheat was 0.4%. Our results showed that, on average, nitrification inhibitors reduced direct N2O emissions by 35% and increased NH3 volatilization by 29%. The average NH3 emission factor was 32% and urease inhibitors reduced NH3 volatilization by 41%. The results showed that indirect N2O emissions from NH3 volatilization should be considered in these conditions.
How to cite: Mirkhani, R., Jabbari Malayeri, M., Naserian Khiabani, B., Mousavi, S. M., Ghafariyan, M. H., Ghavami, M. S., Dercon, G., Shorafa, M., and Kheng Heng, L.: Meta-analysis of direct nitrous oxide emissions and ammonia volatilization from irrigated wheat in calcareous soils under semi-arid conditions, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1026, https://doi.org/10.5194/egusphere-egu25-1026, 2025.
