# Coupling easily numerical models using the VSoil modelling platform

Nicolas Beudez¹, Nicolas Moitrier¹, Nathalie Moitrier¹, Cédric Nouguier¹, Stéphane Ruy¹, François Lafolie¹
¹INRAE, Avignon Université, UMR EMMAH, F-84914, Avignon, France

INRAO

AVIGNON
UNIVERSITÉ

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## 1. Scientific needs

To provide a detailed representation of soil functioning, it is necessary to couple a large number of models that represent the various processes taking place within it.

## 2. The VSoil collaborative platform

An open-source platform under Apache 2 licence designed to aid the development of numerical models at the soil profile scale describing physical, chemical and biological processes in soil and its interactions with climate, plants and anthropic activities.

### 2.1 The VSoil software suite

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YOU CAN START ANY STEP

### Informations, contact and support

You can access the VSoil's website here:

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You can contact us here: vsoil@inrae.fr

### Support

- VSoil team: 1 researcher, 3 software engineers and 1 scientific computing engineer;

- reference scientists for the models.

### Acknowledgements

We thank Annette Bérard, André Chanzy, Claude Doussan, Eric Michel and Céline Pelosi for their advices in the conception of this poster.

### 2.2 Particular features

- Open library: currently ~700 variables, ~50 processes, ~150 modules and ~20 models. Examples of processes: water, heat and gas transfers, organic matter dynamics, solute transport, evapotranspiration...

- Automatic generation of:

- model's source code and graphical user interface;

- output files;

- R scripts for sensitivity analysis and parameter estimation.

- Remote computing on servers or clusters.

- 'Stop and resume' functionality (for example to update weather data during simulation).

- VSoil models can be integrated into third-party models / platforms.

- A collaborative tool: exchanges between users (export / import system) + capitalisation by the VSoil team (sharing with the community).

## 3. Some use cases

### 3.1 Modelling pedogenesis processes

<figure><img src="image_6.png" /><figcaption>Processes involved in the OC_VGEN model (H. Chaif)</figcaption></figure>

Funding: INRAE, ADEME, partners: INRAE, ARVALIS.

OC_VGEN (Keyvanshokouhi et al., 2019): model developed in VSoil to simulate the evolution of soil properties at the century scale in a vertical soil profile.

Several processes are represented into dedicated modules adapted from the SoilGen (Finke and Hudson, 2008) and PASTIS (Lafolie, 1991 and Findeling et al., 2007) models.

Introduced time-adaptive meshing in VSoil:

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save computing time on century-scale simulations

Recent improvement of OC_VGEN model:

add a module to take account of volume change of soil over time (Chaif et al., 2025)

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better prediction of bulk density evolution at the century scale

Automatically generated GUI for configuring the model (vsoil-models)

### 3.2 Building a model for predicting the risk of rutting in forest soils

Funding: ADEME, partners: ONF, CNPF-IDF, FCBA, INRAE.

Context: forestry machine traffic is one of the main causes of physical degradation of forest soils and, consequently, of forest stands.

Forestry machinery travels on dedicated tracks known as skid trails, whose practicability must be maintained over the long-term.

<figure><img src="image_9.png" /><figcaption>Ruts in the Grand-Pays national forest (Meuse, France) – March 2021</figcaption></figure>

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Development of a climate service prototype for real-time prediction of the water status of skid trails over the next 14 days:

observed and forecast weather data (ECMWF)

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model to simulate the degree of water saturation of skid trails

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ask minimum information to forestry operators

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= predicting the risk of rutting

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Steps:

1. Building the model within VSoil:

1D mechanistic model of the soil-litter-tree-atmosphere system to simulate water transfer in an undisturbed and compacted forest soil (Martin et al., 2024).

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module for calculating soil practicability indices

2. Sensitivity analysis to identify most important model's parameters on the number of practicable days predicted: use of R packages through VSoil.

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Graphical selection of processes and associated modules (vsoil-models)

## 4. Perspectives

- New models available soon (ex: hydro-geophysics).

- Development of 3D modelling to take better account of soil heterogeneity.

- Access to free forecast and observed weather data to feed models.

## References

Lafolie (1991), DOI: 10.1007/bf01051129

Findeling et al. (2007), DOI: 10.1111/j.1365-2389.2006.00826.x

Finke and Hudson (2008), DOI: 10.1016/j.geoderma.2008.01.017

Keyvanshokouhi et al. (2019), DOI: 10.1016/j.scitotenv.2018.10.236

Martin et al. (2024), DOI: 10.1186/s13595-024-01265-4

Chaif et al. (2025), DOI: 10.1016/j.geoderma.2025.117228