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Titre :
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Field shrinkage curves of a swelling clay soil : analysis of multiple structural swelling and shrinkage phases in the prisms of a Vertisol
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Auteurs :
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Y. Cabidoche ;
S. Ruy
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Type de document :
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article/chapitre/communication
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Année de publication :
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2001
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Format :
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p. 143-160
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Langues:
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= Anglais
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Catégories :
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SOL GEOLOGIE
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Mots-clés:
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ARGILE
;
RETRAIT
;
INFILTRATION
;
POROSITE
;
GONFLEMENT
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Résumé :
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The variations in the layer thickness of a Vertisol cropped with sugarcane were recorded under natural conditions for several months. Drainage pipes were installed at 1.10 m depth to drain water quickly from macro-cracks. The soil gravimetric water content was measured from the surface to 1.10 m depth at weekly intervals. The relation between soil water content and soil bulk specific volume (shrinkage curve) is not unique. A significant structural swelling or shrinkage can occur at any water content of the clay matrix while the macro-cracks remain air-filled. The variations in structural water content account for >60% and 80% of the total water content variations, respectively, in topsoil and subsoil. In the latter, the intra-prism structural porosity is filled and then emptied prior to matric porosity. This explains the disappearance of the water stress in such dry soil after any rainfall event. A more detailed description of the intra-prism structural porosity is required for a better understanding of the processes. Our work suggests that this porosity is mainly formed by planar inter-aggregate voids in the tilled layers, whereas its shape is tubular in the deeper layers.
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Source :
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Australian journal of soil research, vol.39
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