Sebastian Doetterl

Last Name

Doetterl

First Name

Sebastian

ORCID

0000-0002-0986-891X

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09646 - Dötterl, Sebastian / Dötterl, Sebastian

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Publications1 - 10 of 123

Parent material geochemistry – and not plant biomass – as the key factor shaping soil organic carbon stocks in European alpine grasslands
Maier, Annina; Macfarlane, Maria E.; Griepentrog, Marco; et al. (2025)
Biogeosciences
Soils represent the largest terrestrial carbon (C) reservoir on Earth. Within terrestrial ecosystems, soil geochemistry can be a strong driver of plant-soil-carbon dynamics, especially in young, less weathered soils. Here, we investigate the impact of potential plant biomass input, soil fertility parameters, and soil organic carbon (SOC) stabilization mechanisms on the distribution of SOC in European alpine grasslands across gradients of geochemically distinct parent materials. We demonstrate that SOC stock accrual and persistence in geochemically young soils, with fraction modern (F14C) values ranging from 0.77–1.06, is heavily dependent on soil mineralogy as a result of parent material weathering, but is not strongly linked to plant biomass. We show potential differences in the importance of geochemical variables and SOC stabilization mechanisms, with the microaggregate soil fraction contributing ≥ 50 % to bulk SOC in the majority of cases. We further show that concentrations of Fe, Al and Mn pedogenic oxides coincide with SOC stock magnitude across an alpine soil geochemical gradient, where SOC stocks range between 8.1–23.2 kg C m−2. Our results highlight that soil fertility and soil mineralogical characteristics, which govern plant C inputs and control C stabilization respectively, play equally crucial roles in predicting SOC contents in alpine soils at an early development stage.
An open-source database for the synthesis of soil radiocarbon data: International Soil Radiocarbon Database (ISRaD) version 1.0
Lawrence, Corey R.; Beem-Miller, Jeffrey; Hoyt, Alison M.; et al. (2020)
Earth System Science Data
Radiocarbon is a critical constraint on our estimates of the timescales of soil carbon cycling that can aid in identifying mechanisms of carbon stabilization and destabilization and improve the forecast of soil carbon response to management or environmental change. Despite the wealth of soil radiocarbon data that have been reported over the past 75 years, the ability to apply these data to global-scale questions is limited by our capacity to synthesize and compare measurements generated using a variety of methods. Here, we present the International Soil Radiocarbon Database (ISRaD; http://soilradiocarbon.org, last access: 16 December 2019), an open-source archive of soil data that include reported measurements from bulk soils, distinct soil carbon pools isolated in the laboratory by a variety of soil fractionation methods, samples of soil gas or water collected interstitially from within an intact soil profile, CO2 gas isolated from laboratory soil incubations, and fluxes collected in situ from a soil profile. The core of ISRaD is a relational database structured around individual datasets (entries) and organized hierarchically to report soil radiocarbon data, measured at different physical and temporal scales as well as other soil or environmental properties that may also be measured and may assist with interpretation and context. Anyone may contribute their own data to the database by entering it into the ISRaD template and subjecting it to quality assurance protocols. ISRaD can be accessed through (1) a web-based interface, (2) an R package (ISRaD), or (3) direct access to code and data through the GitHub repository, which hosts both code and data. The design of ISRaD allows for participants to become directly involved in the management, design, and application of ISRaD data. The synthesized dataset is available in two forms: the original data as reported by the authors of the datasets and an enhanced dataset that includes ancillary geospatial data calculated within the ISRaD framework. ISRaD also provides data management tools in the ISRaD-R package that provide a starting point for data analysis; as an open-source project, the broader soil community is invited and encouraged to add data, tools, and ideas for improvement. As a whole, ISRaD provides resources to aid our evaluation of soil dynamics across a range of spatial and temporal scales.
Perspectives on the misconception of levitating soil aggregates
Garland, Gina; Koestel, John; Johannes, Alice; et al. (2024)
Soil
Soil aggregation is an important process in nearly all soils across the globe. Aggregates develop over time through a series of abiotic and biotic processes and interactions, including plant growth and decay, microbial activity, plant and microbial exudation, bioturbation, and physicochemical stabilization processes, and are greatly influenced by soil management practices. Together, and through feedback with organic matter and primary soil particles, these processes form dynamic soil aggregates and pore spaces, which jointly constitute a soil's structure and contribute to overall soil functioning. Nevertheless, the concept of soil aggregates is hotly debated, leading to confusion about their function or relevancy to soil processes. We argue here that the opposition to the concept of soil aggregation likely stems from the fact that the methods for the characterization of soil aggregates have largely been developed in the context of arable soils, where tillage promotes the formation of distinct soil aggregates that are easily visible in the topsoil. We propose that the widespread use of conceptual figures showing detached and isolated aggregates can be misleading and has contributed to the skepticism towards soil aggregates. However, the fact that we do not always see discrete aggregates within soils in situ does not mean that aggregates do not exist or are not relevant to the study of soil processes. Given that, by definition, soil aggregates consist of any group of soil particles that cohere more strongly to each other than neighboring particles, aggregates may, but do not necessarily need to be, bordered by pore space. Here, we illustrate how aggregates can form and dissipate within the context of undisturbed, intact soils, highlighting the point that aggregates do not necessarily need to have a discrete physical boundary and can exist seamlessly embedded in the soil. We hope that our contribution helps the debate on soil aggregates and supports the foundation of a shared understanding on the characterization and function of soil structure.
Soil Carbon Saturation: What Do We Really Know?
Georgiou, Katerina; Angers, Denis; Champiny, Ryan E.; et al. (2025)
Global Change Biology
Managing soils to increase organic carbon storage presents a potential opportunity to mitigate and adapt to global change challenges, while providing numerous co-benefits and ecosystem services. However, soils differ widely in their potential for carbon sequestration, and knowledge of biophysical limits to carbon accumulation may aid in informing priority regions. Consequently, there is great interest in assessing whether soils exhibit a maximum capacity for storing organic carbon, particularly within organo–mineral associations given the finite nature of reactive minerals in a soil. While the concept of soil carbon saturation has existed for over 25 years, recent studies have argued for and against its importance. Here, we summarize the conceptual understanding of soil carbon saturation at both micro- and macro-scales, define key terminology, and address common concerns and misconceptions. We review methods used to quantify soil carbon saturation, highlighting the theory and potential caveats of each approach. Critically, we explore the utility of the principles of soil carbon saturation for informing carbon accumulation, vulnerability to loss, and representations in process-based models. We highlight key knowledge gaps and propose next steps for furthering our mechanistic understanding of soil carbon saturation and its implications for soil management.
Soil Microbial Populations Shift as Processes Protecting Organic Matter Change During Podzolization
Vermeire, Marie-Liesse; Cornélis, Jean Thomas; Van Ranst, Eric; et al. (2018)
Frontiers in Environmental Science
In the upper part of the solum of mineral soils, soil organic and mineral constituents co-evolve through pedogenesis, that in turn impacts the transformation and stabilization of soil organic matter (SOM). Here, we assess the reciprocal interactions between soil minerals, SOM and the broad composition of microbial populations in a 530-year chronosequence of podzolic soils. Five pedons, derived from beach sand, are studied. From young to old soils, net acidification parallels mineral dissolution and the formation of eluvial and illuvial horizons. Organo-mineral associations (OMA) accumulate in the illuvial B horizon of the older soils (330–530 years). Apart from contributing to SOM stabilization and protection, organo-mineral compounds progressively fill up interparticle voids. The subsequent loss of porosity leads to horizon induration, decrease of hydraulic conductivity, which promote redoximorphic processes. While recalcitrant SOM is preserved in the topsoil of the old soils, the largest quantity of protected SOM occurs in the indurated, temporalily waterlogged B horizons, through both the OMA accumulation and inhibition of microbial decomposition. SOM protection is thus both time- and horizon-specific. The microbiota also evolve along the chronosequence. Fungi dominate in all horizons of the younger soils and in the topsoil of the older soils, while bacteria prevail in the cemented B horizons of older soils. This shift in microbial community composition is due to the interdependent co-evolution of SOM and minerals during pedogenesis. Our results call for considering the microenvironment and parameters inherent to decomposer microorganisms to understand SOM protection processes in soils.
Influence of paddy rice cultivation on chemical and physical properties of two contrasting soil types in Switzerland
Widmer, Alina; Sommer, Marlies; Doetterl, Sebastian; et al. (2025)
Advancing Soil Knowledge for a Sustainable Future – EUROSOIL 2025 Book of Abstracts”
Recently, paddy rice cultivation has become possible north of the Alps in Switzerland. This new cultivation system has raised many questions regarding the suitability of different soil types and the practicability of crop rotation. In this study, we focus on two contrasting soils (Gleysol and Cambisol) that differ in their soil hydraulic properties and carbon content but are both managed by the same farmer. We collected soil samples before the fields were converted to paddy rice cultivation, after the first growing season before harvest, and one year after the initial sampling to observe changes in chemical and physical soil properties. Results suggest that both soils experienced significant deterioration in their physical properties (pore connectivity, permeability, bulk density, and porosity) in the topsoil and plow layer, even without puddling measures. However, after winter fallow, the Cambisol showed signs of structural recovery by increasing porosity and connectivity in topsoil macropores, while the Gleysol’s soil structure mostly remained unchanged. Links between soil structure, aggregate stability, and carbon dynamics will be presented at the conference. Preliminary conclusions indicate that the Gleysol is better suited for paddy rice cultivation compared to the Cambisol, as water infiltration is easily inhibited by disrupting the pore system after just one season. However, the limited recovery potential of the Gleysol’s soil structure also indicates more challenging conditions if farmers want to rotate paddy rice with upland crops, making the Cambisol more suitable for different crops
Mitigating greenhouse gas emissions from managed organic soils in the temperate zone by paddy rice cultivation
Widmer, Alina; Tamagni, Lisa; Wüst-Galley, Chloé; et al. (2024)
EGUsphere
Large areas of European peatlands have been drained for agriculture, but drained organic soils are a strong source of carbon dioxide (CO2). Reinstalling high water tables would inhibit further peat oxidation and reduce CO2 and nitrous oxide (N2O) emissions, but most cash crops do not grow in waterlogged conditions. Paddy rice cultivation could offer a new option for continuing the agricultural use of these soils under wet conditions. However, paddy rice cultivation is known to be a strong source of methane (CH4), which might cancel out the potential climate benefit from reduced CO2 and N2O emissions. The main aim of this study was, therefore, to quantify for the first time the greenhouse gas (GHG) balance of paddy rice grown on organic soil in the temperate climate zone of the Swiss Plateau. In an outdoor mesocosm experiment, we measured the greenhouse gases CO2, CH4, and N2O with manual chambers on a weekly to biweekly interval for one year. During the experiment, rice (Oryza sativa L.) was cultivated under flooded conditions with mid-season drainage on organic soil. As a reference treatment, ley was grown on drained organic soil (water table -100 cm). Preliminary results from the growing season (April - October) including planting and harvest suggest that the overall GHG balance of paddy rice cultivation on organic soil (9.3 ± 1.9 t CO2 eq. ha-1 including harvest exports) was significantly lower than of ley grown on drained organic soil (27.9 ± 5.0 t CO2 eq. ha-1 including harvest exports). This difference was mainly attributed to the strong reduction in ecosystem respiration under flooded conditions compared to ley on drained organic soil. Paddy rice cultivation was a source of methane (49.2 ± 19.7 kg CH4 ha-1), while the drained organic soil covered with ley was a CH4 sink (-0.6 ± 0.1 kg CH4 ha-1). The flooded conditions in the paddy rice mesocosms significantly lowered N2O emissions (0.7 ± 0.3 kg N2O ha-1) compared to drained grassland (4.7 ± 3.1 kg N2O ha-1). N2O and CH4 accounted for 16.0 ± 6.8 % of the total GHG balance in the rice on organic soil treatment, whereas it was only 4.9 ± 2.6 % in the ley on drained organic soil. Together, we show that paddy rice cultivation on organic soil is a valid alternative to upland agriculture in the temperate zone and offers significant GHG emission reduction potentials.
The role of geochemistry in organic carbon stabilization against microbial decomposition in tropical rainforest soils
Reichenbach, Mario; Fiener, Peter; Garland, Gina; et al. (2021)
Soil
Stabilization of soil organic carbon (SOC) against microbial decomposition depends on several soil properties, including the soil weathering stage and the mineralogy of parent material. As such, tropical SOC stabilization mechanisms likely differ from those in temperate soils due to contrasting soil development. To better understand these mechanisms, we investigated SOC dynamics at three soil depths under pristine tropical African mountain forest along a geochemical gradient from mafic to felsic and a topographic gradient covering plateau, slope and valley positions. To do so, we conducted a series of soil C fractionation experiments in combination with an analysis of the geochemical composition of soil and a sequential extraction of pedogenic oxides. Relationships between our target and predicting variables were investigated using a combination of regression analyses and dimension reduction. Here, we show that reactive secondary mineral phases drive SOC properties and stabilization mechanisms together with, and sometimes more strongly than, other mechanisms such as aggregation or C stabilization by clay content. Key mineral stabilization mechanisms for SOC were strongly related to soil geochemistry, differing across the study regions. These findings were independent of topography in the absence of detectable erosion processes. Instead, fluvial dynamics and changes in soil moisture conditions had a secondary control on SOC dynamics in valley positions, leading to higher SOC stocks there than at the non-valley positions. At several sites, we also detected fossil organic carbon (FOC), which is characterized by high C/N ratios and depletion of N. FOC constitutes up to 52.0 +/- 13.2 % of total SOC stock in the C-depleted subsoil. Interestingly, total SOC stocks for these soils did not exceed those of sites without FOC. Additionally, FOC decreased strongly towards more shallow soil depths, indicating decomposability of FOC by microbial communities under more fertile conditions. Regression models, considering depth intervals of 0-10, 30-10 and 60-70 cm, showed that variables affiliated with soil weathering, parent material geochemistry and soil fertility, together with soil depth, explained up to 75 % of the variability of SOC stocks and Delta C-14. Furthermore, the same variables explain 44 % of the variability in the relative abundance of C associated with microaggregates vs. free-silt- and-clay-associated C fractions. However, geochemical variables gained or retained importance for explaining SOC target variables when controlling for soil depth. We conclude that despite long-lasting weathering, geochemical properties of soil parent material leave a footprint in tropical soils that affects SOC stocks and mineral-related C stabilization mechanisms. While identified stabilization mechanisms and controls are similar to less weathered soils in other climate zones, their relative importance is markedly different in the tropical soils investigated.
Parent material modulated effects of soil degradation on fertility and organic carbon of tropical cropland soils in Eastern Africa
Summerauer, Laura; Bamba, Fernando; Akoraebirungi, Bendicto; et al. (2024)
EGUsphere
Deforestation for cropland expansion in the sloping landscapes along the East African Rift system causes severe soil erosion and thus the loss of fertile, organic rich topsoil. However, the varying effect of land degradation in the region on soils developed from different parent material - which may influence soil fertility and carbon stabilization - are still largely unknown. To examine these factors, we compared soil organic carbon (SOC) and soil fertility indicators in undisturbed forest topsoils with cropland hillslope topsoils along a chronosequence after deforestation (2–7, 10–20, 20–40, > 60 years of cropping, land abandonment) on mafic (South Kivu, Democratic Republic of Congo) and felsic parent material (western Uganda). From previous studies, we expected higher soil fertility and SOC contents and therefore slower degradation on mafic soils due to the higher amounts of clay and pedogenic metal phases which stabilize SOM and thus further maintain soil fertility. However, we found similar SOC contents on both parent materials and a consistent decrease with time after deforestation. SOC values were significantly lower in soils that were cleared more than 60 years ago, compared to cropland which was cleared 2–7 years ago and nearby undisturbed forest topsoils (0–10 cm soil depth). While the effective cation exchange capacity (ECEC) positively correlated with SOC in soils on felsic parent material, this was not observed in soils with mafic parent material, where it correlated with mineralogical proxies (total reserves in bases). In both regions, SOC did not correlate with clay content. Mid-Holocene carbonate volcanism appears to have offset soil degradation in the felsic region, contributing to higher pH and ECEC and impeding land abandonment due to the maintenance of acceptable soil fertility levels. Surprisingly, abandoned cropland sites in the mafic region still had an average SOC content of 14–29 g kg-1 in topsoils, likely due to strong fixation of SOC with reactive metal phases; however, they were characterized by extremely low pH values and high Al3+ mobility, combined with low available nutrient status. Our results emphasize that soil fertility and carbon stabilization are reliant on the mineral composition of the underlying parent material, even in deeply weathered soils of the humid tropics. Soil organic matter in degraded tropical cropland soils does not appear to be a reliable indicator of soil fertility.
Soils in a changing world
Doetterl, Sebastian (2021)
EGUsphere
Good time for soil scientists, bad time for soils? Join me at my Soil System Sciences - OECS award lecture where I will highlight how Global Change affects soils across ecosystems and what this means for future plant-soil interactions and biogeochemical cycles in a warming, crowded world out of balance.Global Change from the Arctic to the Tropics has accelerated drastically in recent decades, subsequently effecting ecosystems everywhere. Soils and biogeochemical cycling within are no exception. For example, how carbon and nutrients are stabilized in and released from soil is highly affected by changing land use and climate. Despite these changes, soil in earth system models is not represented mechanistically, but rather given a mostly budgetary "black box" function. No methodological framework is available that accounts for the combined effects of climate, geochemistry and disturbance on soil dynamics at larger scales. In addition, most of our process understanding of biogeochemical cycling in soils is derived from data-rich temperate regions. This data has limited applicability in low latitudinal (tropics) or high latitudinal (boreal/subpolar) climate zones, where soils have different properties and drastically different developmental histories.In my talk I will illustrate with a few examples how the gaps in our understanding of soil processes across climate zones and dismissing lateral soil fluxes leads to large uncertainties in predicting future trajectories of the global carbon cycle. I will highlight how the interactions of weathering and disturbance can influence and dominate biogeochemical cycles and microbial processes in soils. I will also discuss some directions where geochemical proxies that are available at the global scale can be useful to model the spatial and temporal patterns of soil carbon storage and turnover.

Publications1 - 10 of 123

Sebastian Doetterl

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