Evapotranspiration―Soil Structure Relationship in West Marshes of France

The soil potentials, facing to the crop fields, are commonly estimated through the calculation of their available water capacity based on the ETP or ETM estimation. The present work introduces the comparison between theoretical and real available water capacity profiles calculated down to 1.00 m depth. The evapotranspiration data are used to the calculation of ETP in an undrained grassland and ETM in two drained corn fields located in the French Atlantic marshlands. The studied soils have acquired specific properties in response to the reclaiming of the clay; dominant primary sediments began since the Middle Age and late drainage works. The theoretical and real profiles are confronted to the tensiometric pressure recording at 30, 60 and 90 cm. The tensiometric pressure behavior and associated premature disconnections of the tensiometric plugs are explained thanks to the soil structure-hydromechanical property relationships: i.e. from ductile state in depth to brittle state in surface.