Modeling the effect of soil organic matter on microaggregate formation in soils and their influence on soil functions

Prof. Peter Knabner1, Dr. Nadja Ray1, M.Sc. Andreas  Rupp1, Dr. Alexander Prechtel1, Prof. Kai Totsche2, Prof. Ingrid Kögel-Knabner3

1University Erlangen-Nürnberg Department Mathematics, D 91058  Erlangen, Germany, 2University Jena Institute for Geosciences Geohydrology, D07749 Jena, Germany, 3Technical University Munich Chair of Soil Science, D85354 Freising, Germany

Microaggregates are the fundamental building blocks of soils and thus important for their structure, properties, and functions. Mathematically based modeling can facilitate the understanding of self-organization, formation, build-up, composition, properties, and stability of microaggregates provided that the complex coupling of biological, chemical and physical processes is taken into account.
Our model is based on a cellular automaton method (CAM) for the pore scale evolution of the solid , biomass and liquid (water, air) phases, all transport and reaction processes are described continuum mechanics based. In the CAM framework, prototypic solid building units quartz (spherical), goethite (needle-like), and illite (platy) are implemented to investigate the formation and self-organization of soil microaggregates. Interaction of these building units by means of stabilizing sticky agents (EPS) in combination with electrostatic attraction/repulsion lead to composite building units and eventually to soil microaggregates. Modern numerical techniques (DG methods) allow for the simulation of the full model The operational, comprehensive model allows rating the influencing factors for the formation of soil microaggregates and also investigating optimal aggregation conditions. Moreover, our modeling approach enables revealing the effect soil organic matter has as nucleus for the aggregation process.

Finally, soil’s characteristic properties such as porosity, effective diffusion tensors and permeabilities for the resulting complex geometries are deduced rigorously on the basis of such a detailed structure evolution and allow for Darcy scale simulations of flow and reactive transport taking into account the pore scale evolution at the level of detail described above. In this way it is possible to assess the impact of microaggregate formation on soil functions.


Biography:

Peter Knabner studied mathematics and computer science in Berlin in Germany. He obtained a doctorate in mathematics 1983 and the habilitation 1988 in Augsburg. In 1992 he became group leader at the Weierstraß Institute in Berlin and in 1994 full professor and chair at the university Erlangen. He serves as associate editor for ‚Computational Geoscience‘.

Peter Knabner is author of more than  180 peer-reviewed publications in applied analysis, numerical mathematics and geohydrology. He is (co) author of 11  textbooks, dealing with numerics of partial differential equations, mathematical modelling, linear algebra and other subjects. He has supervised more than 40 doctorate students and habilitation candidates.

Since the 1980ies Knabner is focused on the derivation, analysis and numerical approximation of mathematical models for flow and transport in porous media. Meanwhile the subjects span up to multiphase multicomponent flows with vanishing/emerging phases, general chemical reaction networks and because of this evolving porous media.

SOIL ORGANIC MATTER

7th International Symposium
Soil Organic Matter

6 – 11 October 2019

Hilton Adelaide

Adelaide, South Australia

Australia

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