Institut für Bodenkunde und Standortslehre

Permanent URI for this collectionhttps://hohpublica.uni-hohenheim.de/handle/123456789/10

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Distribution of Al, Fe, Si, and DOC between size fractions mobilised from topsoil horizons with progressing degree of podzolisation
(2022) Krettek, Agnes; Stein, Mathias; Rennert, Thilo
Aluminium, Fe, Si, and dissolved organic C (DOC) accumulate in the subsoil of Podzols after mobilisation in the topsoil. We conducted laboratory experiments with topsoil horizons with progressing degree of podzolisation by irrigation with artificial rainwater at varying intensity and permanence. We monitored the concentrations and distribution of mobilised Al, Fe, Si, and DOC between size fractions (< 1000 Dalton, 1 kDa– < 0.45 µm, and > 0.45 µm). Total eluate concentrations were increased at the onset of the experiments and after the first irrigation interruption, indicating non-equilibrium release. There was no statistical effect of the degree of podzolisation on element concentrations. Release of Al, Fe, and DOC was mostly dominant in the fraction 1 kDa– < 0.45 µm, indicating metals complexed by larger organic molecules and colloids. Silicon released was dominantly monomeric silicic acid < 1 kDa. Particularly with the least podzolised soils, Al and Si concentrations < 1 kDa might have been controlled by short-range ordered aluminosilicates, while their transport in colloidal form was unlikely. Our study pointed to both quantitative and qualitative seasonality of element release during podzolisation, to decoupling of Al and Si release regarding size, and to different minerals that control element release as a function of the degree of podzolisation.
A global database of soil microbial phospholipid fatty acids and enzyme activities
(2025) van Galen, Laura G.; Smith, Gabriel Reuben; Margenot, Andrew J.; Waldrop, Mark P.; Crowther, Thomas W.; Peay, Kabir G.; Jackson, Robert B.; Yu, Kailiang; Abrahão, Anna; Ahmed, Talaat A.; Alatalo, Juha M.; Anslan, Sten; Anthony, Mark A.; Araujo, Ademir Sergio Ferreira; Ascher-Jenull, Judith; Bach, Elizabeth M.; Bahram, Mohammad; Baker, Christopher C. M.; Baldrian, Petr; Bardgett, Richard D.; Barrios-Garcia, M. Noelia; Bastida, Felipe; Beggi, Francesca; Benning, Liane G.; Bragazza, Luca; Broadbent, Arthur A. D.; Cano-Díaz, Concha; Cates, Anna M.; Cerri, Carlos E. P.; Cesarz, Simone; Chen, Baodong; Classen, Aimeé T.; Dahl, Mathilde Borg; Delgado-Baquerizo, Manuel; Eisenhauer, Nico; Evgrafova, Svetlana Yu.; Fanin, Nicolas; Fornasier, Flavio; Francisco, Romeu; Franco, André L. C.; Frey, Serita D.; Fritze, Hannu; García, Carlos; García-Palacios, Pablo; Gómez-Brandón, María; Gonzalez-Polo, Marina; Gozalo, Beatriz; Griffiths, Robert; Guerra, Carlos; Hallama, Moritz; Hiiesalu, Inga; Hossain, Mohammad Zabed; Hu, Yajun; Insam, Heribert; Jassey, Vincent E. J.; Jiang, Lili; Kandeler, Ellen; Kohout, Petr; Kõljalg, Urmas; Krashevska, Valentyna; Li, Xiaofei; Lu, Jing-Zhong; Lu, Xiankai; Luo, Shan; Lutz, Stefanie; Mackie-Haas, Kathleen Allison; Maestre, Fernando T.; Malmivaara-Lämsä, Minna; Mangelsdorf, Kai; Manjarrez, Maria; Marhan, Sven; Martin, Ashley; Mason, Kelly E.; Mayor, Jordan; McCulley, Rebecca L.; Moora, Mari; Morais, Paula V.; Muñoz-Rojas, Miriam; Murugan, Rajasekaran; Nottingham, Andrew T.; Ochoa, Victoria; Ochoa-Hueso, Raúl; Oja, Jane; Olsson, Pål Axel; Öpik, Maarja; Ostle, Nick; Peltoniemi, Krista; Pennanen, Taina; Pescador, David S.; Png, G. Kenny; Poll, Christian; Põlme, Sergei; Potapov, Anton M.; Priemé, Anders; Pritchard, William; Puissant, Jeremy; Rocha, Sandra Mara Barbosa; Rosinger, Christoph; Ruess, Liliane; Sayer, Emma J.; Scheu, Stefan; Sinsabaugh, Robert L.; Slaughter, Lindsey C.; Soudzilovskaia, Nadejda A.; Sousa, José Paulo; Stanish, Lee; Sugiyama, Shu-ichi; Tedersoo, Leho; Trivedi, Pankaj; Vahter, Tanel; Voriskova, Jana; Wagner, Dirk; Wang, Cong; Wardle, David A.; Whitaker, Jeanette; Yang, Yuanhe; Zhong, Zhiwei; Zhu, Kai; Ziolkowski, Lori A.; Zobel, Martin; van den Hoogen, Johan
Soil microbes drive ecosystem function and play a critical role in how ecosystems respond to global change. Research surrounding soil microbial communities has rapidly increased in recent decades, and substantial data relating to phospholipid fatty acids (PLFAs) and potential enzyme activity have been collected and analysed. However, studies have mostly been restricted to local and regional scales, and their accuracy and usefulness are limited by the extent of accessible data. Here we aim to improve data availability by collating a global database of soil PLFA and potential enzyme activity measurements from 12,258 georeferenced samples located across all continents, 5.1% of which have not previously been published. The database contains data relating to 113 PLFAs and 26 enzyme activities, and includes metadata such as sampling date, sample depth, and soil pH, total carbon, and total nitrogen. This database will help researchers in conducting both global- and local-scale studies to better understand soil microbial biomass and function.
How land-use intensity affects sexual and parthenogenetic oribatid mites in temperate forests and grasslands in Germany
(2021) Wehner, Katja; Schuster, Romina; Simons, Nadja K.; Norton, Roy A.; Blüthgen, Nico; Heethoff, Michael
Intensive land use has been shown to alter the composition and functioning of soil communities. Due to their low dispersal ability, oribatid mites are particularly vulnerable to land-use intensification and species which are not adjusted to management-related disturbances become less abundant. We investigated how different land-use parameters in forests and grasslands affect oribatid mite diversity and abundance, with a focus on: (1) species-level impacts, by classifying species as increasing (‘winners’) or decreasing (‘losers’) in abundance with higher land-use intensity, and (2) reproductive impact, by investigating whether sexual and parthenogenetic species react differently. We collected 32,542 adult oribatid mites in 60 forests and grasslands of known land-use intensity in two regions of Germany. Diversity and total abundance as well as the proportion of sexual species were higher in forests than in grasslands. Diversity declined with higher land-use intensity in forests, but increased with higher mowing and fertilization in grasslands. Depending on land-use parameter and region, abundance either declined or remained unaffected by increasing intensity. Gravidity was higher in sexual than in parthenogenetic species and sexuals had 1.6× more eggs per gravid female. Proportions of sexual species and gravid females decreased with land-use intensity in forests, but increased with mowing in grasslands. At the species level, 75% of sexuals and 87.5% of parthenogens were ‘losers’ of higher percentages of dead wood originating from management-related disturbances. Across land-use parameters and habitats, a similar proportion of sexual and parthenogenetic oribatid mite species were ‘losers’ of high land-use intensity. However, ‘winner’ species were more common among sexuals.
Interactions between cover crops and soil microorganisms increase phosphorus availability in conservation agriculture
(2021) Hallama, Moritz; Pekrun, Carola; Pilz, Stefan; Jarosch, Klaus A.; Frąc, Magdalena; Uksa, Marie; Marhan, Sven; Kandeler, Ellen
Aims: An essential task of agricultural systems is to improve internal phosphorus (P) recycling. Cover crops and tillage reduction can increase sustainability, but it is not known whether stimulation of the soil microbial community can increase the availability of soil organic P pools. Methods: In a field experiment in southwest Germany, the effects of a winter cover crop mixture (vs. bare fallow) and no-till (vs. non-inversion tillage) on microbial P-cycling were assessed with soybean as the main crop. Microbial biomass, phospholipid fatty acids (PLFAs), P cycling enzymes, and carbon-substrate use capacity were linked for the first time with the lability of organic P pools measured by enzyme addition assays (using phosphodiesterase, non-phytase-phosphomonoesterase and fungal phytase). Results: Microbial phosphorus, phosphatase, and fatty acids increased under cover crops, indicating an enhanced potential for organic P cycling. Enzyme-stable organic P shifted towards enzyme-labile organic P pools. Effects of no-till were weaker, and a synergy with cover crops was not evident. Conclusions: In this experiment, cover crops were able to increase the microbially mediated internal P cycling in a non-P-limited, temperate agroecosystems.
The mineralosphere—interactive zone of microbial colonization and carbon use in grassland soils
(2021) Boeddinghaus, Runa S.; Marhan, Sven; Gebala, Aurelia; Haslwimmer, Heike; Vieira, Selma; Sikorski, Johannes; Overmann, Jörg; Soares, Margarida; Rousk, Johannes; Rennert, Thilo; Kandeler, Ellen
To improve our understanding of early microbial colonization of pristine minerals and their group-specific C utilization, we exposed minerals (illite/goethite/quartz) amended with artificial root exudates (ARE, glucose, and citric acid) in grassland soils for a period of 24 weeks. FTIR spectra indicated that mineral-associated ARE were used within the first 2 weeks of exposure and were replaced by other carbohydrates derived from living or dead cells as well as soil-borne C sources transported into the mineralosphere after heavy rain events. Fungi and Gram-positive bacteria incorporated ARE-derived C more rapidly than Gram-negative bacteria. Gram-negative bacteria presumably profited indirectly from the ARE by cross-feeding on mineral-associated necromass of fungi and Gram-positive bacteria. The Gram-negative bacterial phyla Verrucomicrobia, Planctomycetes, Gemmatimonadetes, Armatimonadetes, and Chloroflexi showed a positive correlation with Gram-negative PLFA abundances. After 24 weeks of exposure in the grassland soils, abundances of soil microorganisms in the mineralosphere reached only 3.1% of the population density in soil. In conclusion, both bacteria and fungi slowly colonize new surfaces such as pristine minerals, but quickly assimilate artificial root exudates, creating an active microbial community in the mineralosphere.
Mobilisation of Al, Fe, and DOM from topsoil during simulated early Podzol development and subsequent DOM adsorption on model minerals
(2021) Krettek, Agnes; Rennert, Thilo
Podzols are characterised by mobilisation of metals, particularly Al and Fe, and dissolved organic matter (DOM) in topsoil horizons, and by immobilisation in subsoil horizons. We mimicked element mobilisation during early podzolisation by irrigating the AE horizon of a Dystric Arenosol with acetic acid at different flow velocities and applying flow interruptions to study rate-limited release in experiments with soil cylinders. We used eluates in batch experiments with goethite and Al-saturated montmorillonite to investigate DOM reactivity towards minerals. Both the flow velocity and flow interruptions affected element release, pointing to chemical non-equilibrium of release and to particles, containing Fe and OM mobilised at larger flow velocity, characteristic of heavy rain or snowmelt. Based on chemical extractions, the source of mobilised Al and Fe, the vast majority of which was complexed by DOM, was no oxide phase, but rather organic. Rate limitation also affected the composition of DOM released. Carboxyl and phenolic species were the most important species adsorbed by both minerals. However, DOM composition affected the extent of DOM adsorption on goethite more distinctly than that on montmorillonite. Our findings evidence that the intensity of soil percolation affects quantitative and qualitative element release during early podzolisation and adsorptive DOM retention in subsoil horizons.
An overall review on influence of root architecture on soil carbon sequestration potential
(2024) Srivastava, R. K.; Yetgin, Ali
Soil carbon sequestration is a vital ecosystem function that mitigates climate change by absorbing atmospheric carbon dioxide (CO2). Root characteristics such as depth, diameter, length, and branching pattern affect soil carbon dynamics through root-soil interactions and organic matter breakdown. Here we review field surveys, laboratory analysis, and mathematical modeling to understand how root structures affect soil carbon storage. Further, certain root features increase soil carbon sequestration, suggesting that selective breeding and genetic engineering of plants could maximize this ecological benefit. However, more research is needed to understand the complex interactions between roots, soil biota, and soil organic matter under changing environmental conditions. In addition, the benefit of climate change mitigation methods and soil carbon models from the inclusion of root architecture was reviewed. Studies in the realm of root-soil interactions encompass a variety of academic fields, including agronomy, ecology, soil science, and plant physiology. Insights into how roots interact with their soil environment and the effects of these interactions on plant health, agricultural productivity, and environmental sustainability have been gained through this research.
Quantification of soil microbial functional genes as potential new method in environmental risk assessment of pesticides
(2025) Stache, Fabian; Ditterich, Franziska; Hochmanová, Zuzana; Hofman, Jakub; Poll, Christian; Kandeler, Ellen
Pesticides can have adverse effects on soil microorganisms, but they are underrepresented in the currently required OECD 216 test for environmental risk assessment of plant protection products (PPP). The guideline monitors soil microbial nitrogen transformation over 28 days, potentially missing long-term effects of persistent pesticides. Additionally, nitrate alone may be not sensitive enough to detect disruptions in microbial functions. We investigated whether functional gene analysis could provide a more sensitive bioindicator of pesticide impact. To compare this method with the standard test, we conducted a microcosm experiment following the OECD 216 experimental setup. To capture long-term effects beyond the typical test period, we extended the incubation duration to 56 days. Four different concentrations of the persistent fungicide boscalid were added based on predicted environmental concentration. We also assessed microbial responses to fungicide exposure by measuring classical soil microbial parameters. According to the standard test, boscalid had no harmful long-term effects on soil microbiota. In contrast, our analysis of functional genes found an overall reduction in the acid phosphatase-encoding phoN gene abundance on Day 56, and correspondingly, in acid phosphatase activity in the highest fungicide treatment. Simultaneously, we observed a tendency towards lower fungal abundance based on measured copy numbers of an ITS region of nuclear ribosomal DNA (rDNA) and increased cumulative CO2 production. These results indicate a fungicide-related response of the microbial community and impaired microbial phosphorus cycling. Extending the experimental period to 56 days revealed long-term effects that would have otherwise been undetected under the typical 28-day test duration.
A slow-fast trait continuum at the whole community level in relation to land-use intensification
(2024) Neyret, Margot; Le Provost, Gaëtane; Boesing, Andrea Larissa; Schneider, Florian D.; Baulechner, Dennis; Bergmann, Joana; de Vries, Franciska T.; Fiore-Donno, Anna Maria; Geisen, Stefan; Goldmann, Kezia; Merges, Anna; Saifutdinov, Ruslan A.; Simons, Nadja K.; Tobias, Joseph A.; Zaitsev, Andrey S.; Gossner, Martin M.; Jung, Kirsten; Kandeler, Ellen; Krauss, Jochen; Penone, Caterina; Schloter, Michael; Schulz, Stefanie; Staab, Michael; Wolters, Volkmar; Apostolakis, Antonios; Birkhofer, Klaus; Boch, Steffen; Boeddinghaus, Runa S.; Bolliger, Ralph; Bonkowski, Michael; Buscot, François; Dumack, Kenneth; Fischer, Markus; Gan, Huei Ying; Heinze, Johannes; Hölzel, Norbert; John, Katharina; Klaus, Valentin H.; Kleinebecker, Till; Marhan, Sven; Müller, Jörg; Renner, Swen C.; Rillig, Matthias C.; Schenk, Noëlle V.; Schöning, Ingo; Schrumpf, Marion; Seibold, Sebastian; Socher, Stephanie A.; Solly, Emily F.; Teuscher, Miriam; van Kleunen, Mark; Wubet, Tesfaye; Manning, Peter
Organismal functional strategies form a continuum from slow- to fast-growing organisms, in response to common drivers such as resource availability and disturbance. However, whether there is synchronisation of these strategies at the entire community level is unclear. Here, we combine trait data for >2800 above- and belowground taxa from 14 trophic guilds spanning a disturbance and resource availability gradient in German grasslands. The results indicate that most guilds consistently respond to these drivers through both direct and trophically mediated effects, resulting in a ‘slow-fast’ axis at the level of the entire community. Using 15 indicators of carbon and nutrient fluxes, biomass production and decomposition, we also show that fast trait communities are associated with faster rates of ecosystem functioning. These findings demonstrate that ‘slow’ and ‘fast’ strategies can be manifested at the level of whole communities, opening new avenues of ecosystem-level functional classification.
Synthesis of short-range ordered aluminosilicates at ambient conditions
(2021) Lenhardt, Katharina R.; Breitzke, Hergen; Buntkowsky, Gerd; Reimhult, Erik; Willinger, Max; Rennert, Thilo
We report here on structure-related aggregation effects of short-range ordered aluminosilicates (SROAS) that have to be considered in the development of synthesis protocols and may be relevant for the properties of SROAS in the environment. We synthesized SROAS of variable composition by neutralizing aqueous aluminium chloride with sodium orthosilicate at ambient temperature and pressure. We determined elemental composition, visualized morphology by microscopic techniques, and resolved mineral structure by solid-state 29Si and 27Al nuclear magnetic resonance and Fourier-transform infrared spectroscopy. Nitrogen sorption revealed substantial surface loss of Al-rich SROAS that resembled proto-imogolite formed in soils and sediments due to aggregation upon freezing. The effect was less pronounced in Si-rich SROAS, indicating a structure-dependent effect on spatial arrangement of mass at the submicron scale. Cryomilling efficiently fractured aggregates but did not change the magnitude of specific surface area. Since accessibility of surface functional groups is a prerequisite for sequestration of substances, elucidating physical and chemical processes of aggregation as a function of composition and crystallinity may improve our understanding of the reactivity of SROAS in the environment.

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