Solid samples used for scaning electron microscopy

DFG-Research Unit 2179 MAD Soil

Microaggregates: Formation and turnover of the structural building blocks of soils
Solid samples used for scaning electron microscopy
Image: Hydrogeologie

The RU 2179 MAD Soil

Exploration and the quantitative characterization of the spatial composition, the microarchitecture, the stability, and the properties of soil microaggregates with a unique combination of sophisticated high-resolution imaging and analytical techniques are the major obcectives of this Research Unit (RU).

The RU is organized in different projects that provide the complementary and specific elemental, chemical, physical, topographic and mechanical information on the soil microaggregates at the micron to submicron scale with overlapping scale ranges.

For this, the first mandatory prerequisite is to separate and isolate soil microaggregates not only according to their different size classes, but also with respect to their mechanical stability (against ultrasonic disruption energy).

The grand goals of this RU  are to

  • gain a model-based mechanistic understanding of the formation, build-up, composition, properties and stability of these basic soil structures and
  • relate that to fundamental target functions of soil: the habitat function for microorganisms, the function as carbon sink and the water-storage function.


We expect that a major advancement of the mechanistic understanding of the target functions of soil will derive from the concomitant application of the above-mentioned techniques to both soil microaggregates isolated from a soil texture toposequence - in the second phase additionally a chronosequence - or collected from a so far unique multi-stable-isotope labeling microcosm experiment. The labeling experiment is designed to explore simultaneously the role of mineral and organic matter key components (57Fe for iron oxides, 29Si for phyllosilicate clay minerals, 13C for extracellular polymeric substances) and key "actors" (15N and 13C for bacteria) in the formation of soil microaggregates. To proof already existing and newly developed theories and to quantitatively analyze the data-based theoretical concepts of soil microaggregate formation, stability and turnover, an explicit continuum scale modeling approach is integrated to fuse the still largely isolated modeling approaches that focus either on flow and transport, biogeochemical cycling, carbon turnover, microstructure formation, or microbial activity. This will be based on the iterative refinement of the conceptual model on the formation of soil microaggregates acknowledging the co-evolution of properties and structure, both being identified as the major factors required to simulate the role of these basic soil structures for the functions of soil.

Impressions (field work)

Soil sampling in the Querfurt depression
Image: Michaela Aehnelt
Sampling ring filled with acre soil near Querfurt
Image: Robert Lehmann
Sampling ring removed from acre soil near Querfurt
Image: Robert Lehmann
Luvisol sampled in a drilling rod
Image: Tom Guhra
Plough horizon above loess sampled near Querfurt
Image: Tom Guhra
Soil sampling with sampling rings
Image: Robert Lehmann
Soil samples inside sampling rings
Image: Katharina Lehmann
Earthworms used in laboratory experiments
Image: Katharina Lehmann


Totsche K.U., Amelung W., Gerzabek M.H., Guggenberger G., Klumpp E., Knief C., Lehndorff E., Mikutta R., Peth S., Prechtel A., Ray N., Kögel-Knabner I. (2018) Microaggregates in soils. Journal of Plant Nutrition and Soil Science 181(1), 104-136. DOI: link

Totsche, K.U., Ray, N. and Kögel-Knabner, I. (2024), Structure–function co-evolution during pedogenesis—Microaggregate development and turnover in soils. J. Plant Nutr. Soil Sci., 187: 5-16. link


Amelung, W., Tang, N., Siebers, N., Aehnelt, M., Eusterhues, K., Felde, V. J. M. N. L., Guggenberger, G., Kaiser, K., Kögel-Knabner, I., Klumpp, E., Knief, C., Kruse, J., Lehndorff, E., Mikutta, R., Peth, S., Ray, N., Prechtel, A., Ritschel, T., Schweizer, S. A., Woche, S. K., Wu, B., Totsche, K. U. (2024). Architecture of soil microaggregates: Advanced methodologies to explore properties and functions. Journal of Plant Nutrition and Soil Science, 187, 17–50. link

Bucka, F. B., Felde, V. J. M. N. L., Peth, S., Kögel-Knabner, I. (2024). Complementary effects of sorption and biochemical processing of dissolved organic matter for emerging structure formation controlled by soil texture. Journal of Plant Nutrition and Soil Science, 187, 51–62. link

Guhra, T., Wonneberger, A., Stolze, K., Ritschel, T., Totsche, K. U. (2024). The functional role of earthworm mucus during aggregation. Journal of Plant Nutrition and Soil Science, 187, 63–76. link

Meyer, N., Kaldun, J., Rodionov, A., Amelung, W., & Lehndorff, E. (2024). Turnover of soil microaggregate-protected carbon and the challenge of microscale analyses. Journal of Plant Nutrition and Soil Science, 187, 143–152. link

Roosch, S., Felde, V. J. M. N. L., Uteau, D., Peth, S. (2024). Exploring the mechanisms of diverging mechanical and water stability in macro-and microaggregates. Journal of Plant Nutrition and Soil Science, 187, 104–117. link

Schweizer, S. A., Aehnelt, M., Bucka, F., Totsche, K. U., Kögel-Knabner, I. (2024). Impact of bare fallow management on soil carbon storage and aggregates across a rock fragment gradient. Journal of Plant Nutrition and Soil Science, 187, 118–129. link

Siebers, N., Voggenreiter, E., Joshi, P., Rethemeyer, J., & Wang, L. (2024). Synergistic relationships between the age of soil organic matter, Fe speciation, and aggregate stability in an arable Luvisol. Journal of Plant Nutrition and Soil Science, 187, 77–88. link

Tang, N., Dultz, S., Gerth, D., & Klumpp, E. (2024). Soil colloids as binding agents in the formation of soil microaggregates in wet-dry cycles: A case study for arable Luvisols under different management. Geoderma, 443, 116830. link

Totsche, K. U., Ray, N., & Kögel‐Knabner, I. (2024). Structure–function co‐evolution during pedogenesis—Microaggregate development and turnover in soils. Journal of Plant Nutrition and Soil Science, 187(1), 5-16. link

Zech, S., Prechtel, A., Ray, N. (2024). Coupling scales in process-based soil organic carbon modeling including dynamic aggregation.Journal of Plant Nutrition and Soil Science,187,130–142. link

Yao, T., Bucka, F., Kögel-Knabner, I., Knief, C. (2024). Organic matter type and soil texture shape prokaryotic communities during early-stage soil structure formation. Journal of Plant Nutrition and Soil Science, 187, 89–103. link


Amelung, W., Meyer, N., Rodionov, A., Knief, C., Aehnelt, M., Bauke, S. L., Biesgen, D., Dultz, S., Guggenberger, G., Jaber, M., Klumpp, E., Kögel-Knabner, I., Nischwitz, V., Schweizer, S. A., Wu, B., Totsche, K. U., Lehndorff, E. (2023). Process sequence of soil aggregate formation disentangled through multi-isotope labelling. - Geoderma, 429: 116226. link

Ritschel, T., Totsche, K. U., (2023). Reductive transformation of birnessite by low-molecular-weight organic acids. - Chemosphere, 325: 138414, link

Ritschel, T., Aehnelt, M., Totsche, K.U., (2023). Organic matter governs weathering rates and microstructure evolution during early pedogenesis.  - Geoderma, 429: 116269, link


Guhra, T., Stolze, K. and Totsche, K. U. (2022). Pathways of biogenically excreted organic matter into soil aggregates. - Soil Biology and Biochemistry, 164: 108483. link

Schweizer, S. A. (2022). Perspectives from the Fritz-Scheffer Awardee 2021: Soil organic matter storage and functions determined by patchy and piled-up arrangements at the microscale. - Journal of Plant Nutrition and Soil Science, 185(6): 694–706. link

Stolze, K., Barnes, A. D., Eisenhauer, N., & Totsche, K. U. (2022). Depth-differentiated, multivariate control of biopore number under different land-use practices. - Geoderma, 418: 115852. link

Tang, N., Siebers, N., Leinweber, P., Eckhardt, K. U., Dultz, S., Nischwitz, V., & Klumpp, E. (2022). Implications of free and occluded fine colloids for organic matter preservation in arable soils. - Environmental Science & Technology, 56(19): 14133–14145. link

Zech, S., Ritschel, T., Ray, N., Totsche, K. U., Prechtel, A. (2022). How water connectivity and substrate supply shape the turnover of organic matter - Insights from simulations at the scale of microaggregates. - Geoderma, 405: 115394. doi: 10.1016/j.geoderma.2021.115394External link

Zech, S., Schweizer, S. A., Bucka, F. B., Ray, N., Kögel-Knabner, I., & Prechtel,
A. (2022). Explicit spatial modeling at the pore scale unravels the interplay of soil organic carbon storage and structure dynamics. - Global Change Biology, 28(15): 4589–4604. link


Bucka, B.F.; Felde, V.J.M.N.L.; Peth, S.; Kögel-Knabner, I. (2021): Disentangling the effects of OM quaility and soil texture on microbially mediated structure formation in artificial model soils. -  Geoderma, 403: 115213. link

Bucka, B.F; Pihlap, E.; Kaiser, J.; Baumgartl, T.; Kögel-Knabner, I. (2021): A small scale test for rapid assesment of the soil development potential in post-mining soils. - Soil  & Tillage Research, 211: 105016. link

Dultz, S., Mikutta, R., Kara, S. N., Woche, S. K., & Guggenberger, G. (2021). Effects of solution chemistry on conformation of self-aggregated tannic acid revealed by laser light scattering. - Science of The Total Environment, 754, 142119. link

Felde, V. J. M. N. L., Schweizer, S. A., Biesgen, D., Ulbrich, A., Uteau, D., Knief, C., Graf-Rosenfellner, M., Kögel-Knabner, I., & Peth, S. (2021). Wet sieving versus dry crushing: Soil microaggregates reveal different physical structure, bacterial diversity and organic matter composition in a clay gradient. - European Journal of Soil Science, 72(2): 810–828. link

Guhra, T.; Ritschel, T.; Totsche, K.U. (2021): The mechanisms of gravity-constrained aggregation in natural colloidal suspensions. - Journal of Colloid and Interface Science, 597: 126-136. link

Kögel-Knabner, I.; Amelung, W. (2021): Soil organic matter in major pedogenic soil groups. - Georderma, 384, 114785. link

Lehndorff, E.; Rodionov, A.; Plümer, L.; Rottmann, P.; Spiering, B.; Dultz, S.; Amelung, W. (2021): Spatial organization of soil microaggregates. - Georderma, 386: 114915. link

Schweizer, S.A., Mueller, C.W., Höschen, C., Ivanov, P., Kögel-Knabner, I., 2021. The role of clay content and mineral surface area for soil organic carbon storage in an arable toposequence. - Biogeochemistry, 156(3): 401-420. link

Sosa, M.V.; Lehndorff, E.; Rodionov, A.; Gocke, M.; Sandhage-Hofmann, A.; Amelung, W. (2021): Micro-scale resolution of carbon turnover in soil - Insights from laser ablation isotope ratio mass spectrometry on water-glass embedded aggregates. - Soil Biology and Biochemistry, 159: 108279. link


Biesgen, D.; Findte, K.; Maarastawi, S.; Knief, C.  (2020): Clay content modulates  differences in bacterial community structure in soil aggregates of different size. - Geoderma, 376: 114544. LinkExternal link

Guhra, T.;  Stolze, K.;  Schweizer, S.; Totsche, K. (2020): Earthworm mucus contributes to the formation of organo-mineral associations in soil. - Soil Biology and Biochemistry, 145: 10778. LinkExternal link

Ivanov, Pavel; Manucharova, N.; Nikolaeva, S.; Safonov, A.; Krupskaya, V.; Chernov, M.; Eusterhues, K.; Totsche, K.U. (2020): Glucose-stimulation of natural microbial activity changes composition, structure and engineering properties of sandy and loamy soils. - Engineering Geology, 265: 105381. LinkExternal link

Krause, L.; Klumpp, E.; Nofz, I.; Missong, A.; Amelung, W.; Siebers, N. (2020): Colloidal iron and organic carbon control soil aggregate formation and stability in arable Luvisols. - Geoderma, 374: 114421. LinkExternal link

Zech, S.; Dultz,S.;  Guggenberger, G.; Prechtel A.; Ray, N. (2020): Microaggregation of goethite and illite evaluated by mechanistic modeling. - Applied Clay Science, 198: 105845. LinkExternal link


Bucka, B.F.;  Kölbl, A.; Uteau, D.; Peth, S.; Kögel-Knabner, I. (2019): Organic matter input determines structure development and aggregate formation in artificial soils. - Geoderma, 354: 113881. LinkExternal link

Dultz, S.; Woche, S.K.; Mikutta, R.; Schrapel, M.; Guggenberger, G. (2019): Size and charge constraints in microaggregation: Model experiments with mineral particle size fractions. - Applied Clay Science, 170: 29-40.  LinkExternal link

Guhra, T.;  Ritschel, T.; Totsche, K.U. (2019): Formation of mineral-mineral and organo-mineral composite building units from microaggregate‐forming materials including microbially produced extracellular polymeric substances. - European Journal of Soil Sciences, 70: 604-615. LinkExternal link

Krause, L.; Biesgen, D.; Treder, A.; Schweizer, A.S.; Klumpp, E., Knief, C.; Siebers, N. (2019): Initial microaggregate formation: Association of microorganisms to montmorillonite-goethite aggregates under wetting and drying cycles. - Geoderma, 351: 250-260.  LinkExternal link

Ritschel, T.; Totsche, K.U. (2019): Modeling the formation of soil microaggregates. - Computers and Geosciences, 127: 36-43. LinkExternal link

Rodionov, A.; Lehndorf, E.; Stremtan, C.S.; Brand, W.A.; Königshoven, H-P., Amelung, W. (2019): Spatial Microanalysis of Natural 13C/12C Abundance in Environmental Samples Using Laser Ablation-Isotope Ratio Mass Spectrometry. - Analytical Chemistry, 91: 6225-6232. LinkExternal link

Rupp, A., Guhra, T., Meier, A., Prechtel, A., Ritschel, T., Ray, N., Totsche, K. U. (2019): Application of a Cellular Automaton Method to Model the Structure Formation in Soils Under Saturated Conditions: A Mechanistic  Approach. - Front. Environ. Sci., 7:170.  LinkExternal link

Schulz, R., Ray, N., Zech, S., Rupp, A., Knabner, P. (2019). Beyond Kozeny-Carman: Predicting the Permeability in Porous Media. -  Transport in Porous Media, 130: 487-512. LinkExternal link

Schweizer, A.S.; Bucka, B.F.;  Graf-Rosenfeller, M.; Kögel-Knabner, I. (2019):  Soil microaggregate size composition and organic matter distribution as affected by clay content. - Geoderma, 355: 113901. LinkExternal link


Dultz, S.; Steinke, H.; Mikutta, R.; Woche, S.K.; Guggenberger, G. (2018): Impact of organic matter types on surface charge and aggregation of goethite. - Colloids Surfaces, A554: 156-168. 

Krause, L.; Rodionov, A.; Schweizer, S.A.; Siebers, N.; Lehndorff, E.; Klumpp, E.; Amelung, W. (2018): Microaggregate stability and storage of organic carbon is affected by clay content in arable Luvisols. - Soil & Tillage Research, 182: 123-129. LinkExternal link

Ray N.; Rupp A.; Schulz R.; Knabner P. (2018): Old and new approaches predicting the diffusion in porous media. - Transport in Porous Media, 124: 803 - 824. 

Ritschel, T.; Schlüter, S.; Köhne, J.M.; Vogel, H.-J.; Totsche, K.U. (2018): Efficient prediction of multi-domain flow and transport in hierarchically structured porous media. - Water Resources Research, 54(11): 9033-9044. doi:  10.1029/2018WR022694

Rupp, A.; Knabner, P.; Dawson, C. (2018): A local discontinuous Galerkin scheme for Darcy flow with internal jumps. - Computational Geosciences, 22/4: 1149-1159. 

Rupp, A.; Totsche, K.U.; Prechtel, A.; Ray, N. (2018). Discrete-continuum multiphase model for structure formation in soils including electrostatic effects. - Frontiers in Environmental Science, 6.  LinkExternal link

Siebers; N.; Abdelrahman, H., Krause, L. ; Amelung, W. (2018): Bias in aggregate geometry and properties after disintegration and drying procedures. - Geoderma, 313: 163-171.

Schweizer, S.; Höschen, C.; Schlüter, S.; Kögel-Knabner, I. ; Mueller, C.W. (2018): Rapid soil formation after glacial retreat shaped by spatial patterns of organic matter accrual in microaggregates. - Global Change Biology, 24(4):  1637-1650. LinkExternal link

Totsche, K.U.; Amelung, W.;  Gerzabek, M.H.; Guggenberger; G.; Klumpp, E.; Knief, C., Lehndorff, E., Mikutta, R.; Peth, S; Prechtel, A.; Ray, N.; Kögel-Knabner, I. (2018.):  Microaggregates in soils. - Journal of Plant Nutrition and Soil Science, 181(1): 104-136.  LinkExternal link


Ray, N.; Rupp, A.; Prechtel, A. (2017): Discrete-continuum multiscale model for transport, biomass development and solid restructuring in porous media -  Advances in Water Resources, 107: 393-404. LinkExternal link

Steffens, M.; Rogge, D.M.; Mueller, C.W.; Höschen, C. ; Lugmeier, J., Kölbl, A.; Kögel-Knabner, I. (2017): Identification of distinct functional microstructural domains controlling C Storage in Soil. -  Environonmental Science & Technology, 51/21: 12182-12189.  LinkExternal link



Kai Uwe Totsche, Prof. Dr
Prof. Dr. Kai Uwe Totsche