Biogeochemical interfaces and colloids

The aim of the research group is the understanding of the role of interfaces and colloids in biogeochemical processes. One focus lies on biogeochemical interactions within the plant-soil compartment and their coupling to surface and groundwater. The exchange and transfer of nutrients in the solid and liquid phase and at their interface are studied from the molecular scale to the field scale using state-of-the-art physico-chemical and analytical methods such as NMR, field flow fractionation (AF4, SPLITT), microscopy (SEM/TEM, fluorescence), and scattering (light, X-ray). This research is supported by process-oriented modelling and enables us to elucidate biogeochemical processes in the fluxes and cycling of essential elements, especially nutrients.

Current and recently finished projects:

New biochars for the improvement of agricultural soil

Biochars – produced by the pyrolysis of biomass – have recently been promoted as a useful soil amendment with a multifunctional use, e.g., sequester carbon (C), recover nutrient elements from waste-streams, fix excess nutrients in soils to reduce environmental risks, and ameliorate soil in terms of nutrient status and aggregate structure. Our project aims at a multifunctional use of biochars for nutrient recovery from manure and soil amelioration with a cascade-use of biochar feedstocks from horticulture. Thus, a recycling and value-added utilization of agricultural residues through combining technologies such as pyrolysis could increase the recoverable energy, close the nutrient recycle loop, and ensure cleaner agricultural production. The NewBIAS consortium will ensure dissemination and exploitation of technology and products and thus will stimulate the bioeconomy in NRW by developed technology and regional resources with a clear global and worldwide focus on innovation through the delivery of a novel value-added chain.

BOOST FUND 2.0 Coordinator


Dr. Nina Siebers

Head of research group "Biogeochemical interfaces and colloids"

  • Institut für Bio- und Geowissenschaften (IBG)
  • Agrosphäre (IBG-3)
Gebäude 16.6 /
Raum 3057
+49 2461/61-96614


Prof. Dr. Pude & Dr. Kraska, INRES - Renewable Resources, University of Bonn
Prof. Dr.-Ing. Quicker & A. Brautlacht & M. Lang, Technology of Fuels, RWTH Aachen
Dr. Küppers & Dr. Nischwitz, ZEA-3: Analytics, Forschungszentrum
Prof. Dr. Vereecken & Prof. Dr. Brüggemann & Dr. Siebers, IBG-3: Agrosphere, Forschungszentrum Jülich
Prof. Dr. Schurr & Dr. Schrey & Dr. Kuhn, IBG-2: Plant Sciences, Forschungszentrum Jülich
Prof. Dr. Walther, Operations Management, RWTH Aachen

Colloidal nutrient transport in a forest ecosystem – from experiment to prediction

Biogeochemical interfaces and colloids

Forest stand-replacing disturbances, whether natural or anthropogenic, can transform forests from carbon sinks to sources, impacting soil water content, structure, and nutrient dynamics. While nutrient cycling in forests is extensively studied, there is a notable gap in understanding the contribution of colloidal transport, particularly in temperate forest ecosystems.

This project addresses this gap by proposing a holistic ecosystem model that integrates water and nutrient fluxes, carbon, nitrogen, and phosphorus storage and release, and forest growth. The model extends the AgroC model to simulate forest stands. Calibration and validation will be performed using data from the TERENO site Wüstebach, including measurements of plant diversity, growth, CO2 fluxes, and soil respiration.

To assess colloidal nutrient transport, the HYDRUS-1D software package will be employed, focusing on natural colloids under changing soil water conditions. The lack of understanding regarding the processes and transport pathways of natural soil colloids is addressed through controlled experiments, aiming to identify source strength and estimate colloid-facilitated nutrient transport.

The proposed approach aims to fill critical knowledge gaps in forest ecosystem modeling, particularly in understanding the long-term consequences of major disturbances. By incorporating colloidal transport into numerical models, the study seeks to enhance predictions of elemental fluxes, especially for phosphorus, and improve the overall sustainability and resilience of ecosystems. The research contributes to advancing the understanding of biogeochemical cycles in forests, emphasizing the need for comprehensive models that capture the complexity of ecosystem responses to environmental changes.

Innovative solutions to sustainable soil phosphorus management

InnoSoilPhos - Innovative solutions to sustainable SoilPhosphorus management

Project in the program "BonaRes - Boden als nachhaltige Ressource für die Bioökonomie" supported by the Federal Ministery of Education

Project executing organization: Jülich

Objectives of InnoSoilPhos

Mineral P-fertilizers are on the one side essential for nutrition of agricultural plants but on the other hand can also cause eutrophication of water bodies. Mineral P-fertilizers are mainly produced from rock phosphate, a limited resource. Due to this limitation future agriculture is facing a huge challenge, namely to ensure the nutrition of humans and the income of farmers as well as limiting the ecological footprint, which is challenging the society as a whole. Therefore, the project InnoSThe aim of the research group is the understanding of the role of colloids and interfaces in biogeochemical processes. The exchange and transfer of nutrients in the solid and liquid phase and at their interface are studied from the molecular scale to the catchment scale using state-of-the-art physico-chemical and analytical methods. This research is supported by process-oriented modelling and enables us to elucidate biogeochemical processes in the fluxes and cycling of essential elements, especially nutrients.

oilPhos intents to provide solutions to this problem in soil and agricultural sciences but also governance options.

In Phases I and II, InnoSoilPhos involved 10 workgroups that tackled the P issue at four different scales: (I) the atomic and molecular scale, (II) the plot-to-field scale, (III) the field-to-catchment scale, and (IV) the societal scale. In addition to University of Rostock (UR) these institutions were involved: the Brandenburgische Technical University Cottbus - Senftenberg (BTU), the Julius-Kühn-Institute (JKI), the TU University of Munich (TUM), the Research Center Jülich (FZJ), the Research Unit Sustainability and Climate Policy Leipzig (FNK) and the Bergische Universität Wuppertal (BUW, Phase II).

Scale (I):

- Fundamental understanding of P-fixation and desorption on soil matrix by quantum-chemical modeling

- The effects of soil microorgansims on P-binding and activation

- Spatial heterogeneity, P-sorption, -stocks & possible –activation/usage in subsoil

Scale (II):

- Alternative P fertilizers, e.g., bone chars are developed and evaluated by pot and field experiments

- Effectiveness of P-fertilization is evaluated by metastudies to prove and improve fertilization recommendations

Scale (III):

- Hot spots and hot moments of P leaching from soil in experimental catchment 

Scale (IV):

- Synthesis of above results, in-deep-analysis of alternative P fertilizers like bone chars

The third phase of InnoSoilPhos is organized according to four stakeholder-oriented scientific goals, to which the WPs of consortium members contribute. These goals logically follow from the scientific achievments of InnoSoilPhos-Phases I and II.

Main goal 1: Improvement of microbial P-mobilization 

Main goal 2: Design, production and testing of „new“ smart P fertilizers from recycling materials 

Main goal 3: P in integrated sustainable nutrient management 

Main goal 4: Reduction of environmentally harmful P-losses at field scale

Microaggregates: formation and turnover of the structural building blocks of soils

The DFG 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.

Letzte Änderung: 09.01.2024