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Variabilité à court terme de la stabilité structurale des sols et processus physico-chimiques associés

Abstract : Soil aggregate stability can be used to estimate soil erodibility, a key parameter in erosion models. To improve the knowledge about the factors and processes controlling aggregate stability, this PhD thesis aimed at analyzing the variability of soil aggregate stability at short time step (a few days) and the physicochemical processes controlling this variability. Field studies allowed characterizing a quick dynamic of aggregate stability for a given soil. Results showed: large differences between surface and sub-surface, a large variability among sites (but a low variability within a given site); and a large variability at short time step in relation with soil water content. Aggregate stability changes at short time step are mainly controlled by physico-chemical processes closely related to wetting-and-drying cycles. A literature review showed that the occurrence of some of these processes needed to be validated; especially for the particle rearrangement. Laboratory experiments showed that the internal structure of aggregates was affected by wetting-and-drying cycles at the millimeter and micrometer scales. However, the observed particle rearrangements could not be strictly related to aggregate stability changes. The results of these experiments confirm the field monitoring: soil water content plays a major role in the changes of aggregate stability at short time step. In most of the cases, the measured differences in aggregate stability corresponded to contrasted erodibilities. Hence, erosion models should include this variability to improve their predictions.
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  • HAL Id : tel-02811504, version 1
  • PRODINRA : 174816

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Baptiste Algayer. Variabilité à court terme de la stabilité structurale des sols et processus physico-chimiques associés. Milieux et Changements globaux. Université d'Orléans, 2012. Français. ⟨tel-02811504⟩

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