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Determination of soil hydraulic properties using the soil pedostructure concept

Braudeau E., Mohtar R.H., Martin P., Jallas E., Crétenet M., Clouvel P.. 2003. In : European Geophysical Society, American Geophysical Union, European Union of Geoscience Joint Assembly, Nice, France, 06-11 april 2003. s.l. : s.n., 1 p.. European Geophysical Society, American Geophysical Union, European Union of Geosciences Joint Assembly, 2003-04-06/2003-04-11, Nice (France).

The observed soil water properties such as Field Capacity, Permanent Wilting Point, Water Potential and Hydraulic Conductivity are expressions of the internal soil structure and are all connected to Water Matric Potential. Our research describes these properties in a context of a new concept of the internal hierarchal soil structure and the tension that exists inside the soil matrix due to the presence of clay particles. This concept will be demonstrated using laboratory experiments of simultaneous and continuous measurements of the soil water potential curve and of the shrinkage and swelling curves. The soil shrinkage curve has been used to explain the hydraulic and functional properties of soil with its assembly of swelling aggregates according to the conceptual pedostructure model. In that model two water pools held in two distinguished macro- and micro-porosity are described in addition to specific characteristics of the primary peds such air entry point, maximum swelling, and plasmic porosity. The water potential will be calculated according to these water pools. In this context, the empirical agronomical soil physical properties like wilting point and field capacity, will be defined relative to a particular hydrostructural state of the soil rather than to a hypothetical soil water potential. These properties could then be accurately determined starting from themeasured shrinkage curve determined by retractometry. (Texte intégral)

Mots-clés : propriété hydraulique du sol; structure du sol

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