# Modelling the interaction between soil processes

Sophie Leguédois

► To cite this version:

Sophie Leguédois. Modelling the interaction between soil processes. SAGA - Soil functions Along a Gradient of Anthropisation. IUFRO 125th Anniversary congress, 2017. hal-02787020

HAL Id: hal-02787020

https://hal.inrae.fr/hal-02787020

Submitted on 5 Jun 2020

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# Modelling the interaction between soil processes

Sophie Leguédois

Geoffroy Séré, Apolline Auclerc, Françoise Watteau, Frédéric Darboux, Christophe Schwartz, Jean Louis Morel
Laboratoire Sols et Environnement, Nancy, France
# Why modelling the interaction between soil processes?

* For ecosystem services assessment

* To quantify the impact of global changes on soil and the role of soil on global changes

- Climate change and C sequestration

- Nitrogen cascade and denitrification

* To be able to represent soil along a gradient of anthropization

- Physical, biological and chemical processes

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# Are processes the same in soils along a gradient of anthropization?

* What are your thoughts after those 4 days of summer school?
# Are processes the same in soils along a gradient of anthropization?

* Processes in “natural” soils

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Simononson (1978)

Shaetzl & Anderson (2005)
# Are processes the same in soils along a gradient of anthropization?

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* Soil processes needed to represent ES in SUITMAs

- A majority of processes similar to those of more natural soils
# Are processes the same in soils along a gradient of anthropization?

* Example: pedogenic processes observed in a Technosol

- Occurrence of a wide variety of processes in SUITMAs

- Unexpected combinations of processes

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**Spolic Technosol**

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# Do processes act the same in soils along a gradient of anthropization?

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* The gradient of quality identified for geochemical and biological parameters highlights the difference of intensity in the processes along the gradient of anthropization

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* Strong interactions between processes
How to model the processes?

* Most of the existing models of soil are process-based and multi-process

- Analysis on 18 existing soil models:

* 83% are process-based

* 67% are multi-process

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# How to model the processes?

* Existing tools to couple process-based models able to cope with the diversity of formalisms (e.g. differential equations, agent-based)

- Coupling platforms like Sol Virtuel, Record

* Bergez et al, 2010

- VLE modelling environment/ DEVS

* Quesnel et al., 2009; Zeigler et al., 2000

- Link with computing and numerical calculus domains

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RECORD

* Methods to handle complex codes with potential instability, difficulty in parametrisation and inverse modelling, high computing demand, and uncertainties on output data

- uncertainty and sensitivity analyses

* Saltelli et al. (2004)

- Bayesian modelling

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## Which processes to model?

### Soil processes needed to represent ES in SUITMAS

Leguédois *et al* (2016)

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* Analysis on 18 existing soil models:

- 60 % represent water transfer

- 73 % represent chemical reactivity

* Developments needed in the modeling of processes from SUITMAS related to:

- structure

- evolution of anthropic OM

- microbiological activities
# Modelling challenge: heterogeneous spatial representation

* Generally poor spatial description of the existing models

* Importance of spatial heterogeneity

- ⇔ ecological intensification, lower fertiliser inputs, and no-tillage

* Doré et al. (2011), Hinsinger et al., (2011)

- ⇔ highly heterogeneous spatial organisations observed in SUITMAs and forested soils

* De Kimpe and Morel (2000), Huot et al. (2013), Monseriée et al. (2009)

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Conclusion

* Soil models have mainly been developed for agricultural or contaminated pollutions

- Main modelled processes related to water transfer and chemical reactivity

- Soil homogeneity due to tillage

* Development needed

- Soil heterogeneity / structure evolution

- Soil biological processes

* Existing technical tool to support complex coupled models

- Coupling platform

- UA and SA