The objective of this work is to derive the soil water retention from thesoil structure without curve-fitting and only using the physical parametersfound irrespective of an experimental retention curve. Two key points underliethe work: (i) the soil suction at drying coincides with that of the soilintra-aggregate matrix and contributive clay; and (ii) both the soil suctionand volume shrinkage at drying depend on the same soil water content. Inaddition the two following results are used: (i) the available two-factor(capillarity and shrinkage) model of clay suction enables one to connect a claysuction and clay water content using the clay matrix structure; and (ii) therecent reference shrinkage curve model based on the concepts of intra-aggregatesoil structure permits one to connect the soil water content at shrinkage withthe water content of the contributive clay. With that the available two-factormodel was essentially modified and, in particular, the effect of adsorbed waterfilm was taken into account. The developed model includes the following inputparameters: the solid density, relative volume of contributive-clay solids,relative volume of contributive clay in the oven-dried state, soil claycontent, aggregate/intra-aggregate mass ratio, and specific volume of lacunarpores in the aggregates at maximum swelling. The validation of the model isbased on available data of water retention and the above input parameters forsix soils. A promising agreement between the predicted and observed waterretention curves was found.
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