[feature] Implement MostGG modifications (2025)

Summary

Implement MostGG modifications published by Bonnard et al., 2025.

Current behavior

Current formalisms of Grassim are based on Ruelle et al., 2018.

Desired behavior

Modify the mechanistic equations of the MostGG model updated in Bonnard et al., 2025 and validate their relevance (except the water part as it will be done with stratification). Modifications include (re-read article to ensure all are covered) :

• fW function with quadratic equation (in plants.py)
• water leached modification
• N leached modif (supplementary condtion)
• limitation of mineralisation and immobilization formulas (in soil.py)
• Norg from OM at initilization (soil.py) => Not done, quid of OM evolution (// carbon module)
• N from rain formula (soil.py) + verify relevance in literature

Those new equation won't replace the current one. The strategy is to add new function and in run_grassim.py, calling the one we want to test

Sources

• Bonnard et al., 2025 : https://www.sciencedirect.com/science/article/pii/S1161030125000164
• Ruelle et al., 2018 : https://www.sciencedirect.com/science/article/abs/pii/S116103011830248X

TO DO

• Re-read article to make a complete list of modifications
• Implement modifications
• Benchmarking with old version for each modif (benchamrking script #149)