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Modélisation des propriétés de rétention en eau des sols caillouteux. Application à l'estimation spatialisée de la réserve utile

Abstract : Stony soils are soils containing a proportion of rock fragments larger than 35%. These soils - including intensive agricultural areas - cover about 30% of the surface of Western Europe. Stony soils are not only more stringent for agricultural production because the farming operations are usually more difficult, but also they are often thin; they then significantly contribute to the groundwater recharge, but are they are very sensitive to winter leaching of nitrate and pesticides. Despite their geographical spread and their specific properties, the stony soils have not been largely studied whereas they present specific scientific problems (variability of phase stony, exchanges between the stony phase and the fine fraction of soil). In that context, this thesis aimed at: i) determining the available water content of rock fragments from rock fragments of sedimentary origin; ii) assessing qualitatively and quantitatively the stoniness of stony soils at field scale; and iii) estimating the effective available water content of stony soils and their hydric functioning for large agricultural areas. From laboratory experiments, we demonstrated that rock fragments were saturated for a water potential of -100 hPa and that their water content at field capacity and at permanent wilting point could be easily estimated from their bulk density, which enable to define robust and operational pedotransfer functions for the estimation of the available water content of rock fragments. Thanks to the analysis of the signal noise of the electrical resistivity, measured in situ by geophysical prospectings, it was possible to assess the stoniness of stony soils at the plot scale. Finally, at the regional scale, we demonstrated that the available water content could be underestimated of about 20 % when the volume and/or properties of rock fragments were not taken into account, which induced overestimations of the hydric deficit of about 20 mm as a mean, with high spatial variability This work will ultimately be used for a better spatial management of agricultural soils, at local and regional scales. Indeed, the new hydric properties will help in improving our knowledge of the environmental spatial soil functioning in order to better estimate some risks (nitrate leaching, greenhouse gas emissions from soils).
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  • HAL Id : tel-02811178, version 1
  • PRODINRA : 40103

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Marion Tetegan. Modélisation des propriétés de rétention en eau des sols caillouteux. Application à l'estimation spatialisée de la réserve utile. Sciences du Vivant [q-bio]. Université d'Orléans, 2011. Français. ⟨tel-02811178⟩

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