TITLE:
Evapotranspiration―Soil Structure Relationship in West Marshes of France
AUTHORS:
R. T. Radimy, P. Dudoignon, J. M. Hillaireau, L. Caner
KEYWORDS:
Evapotranspiration, Available Water Capacity, Soil Structure, Clay Dominant Soils, Plant Soil Interaction
JOURNAL NAME:
Journal of Water Resource and Protection,
Vol.6 No.9,
June
26,
2014
ABSTRACT: 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 available water capacity profiles are calculated from
the ETP and ETM data and from the soil moisture profiles respectively, from
June to October 2013. 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. The vertical evolutions of the real profiles are
explained facing to the plant growing, pluviometry and water nape levels. Their
behavior and their shifts from the linear “theoretical” ETP or ETM profiles
clearly show the advance of the desiccation front and consequently the kinetics
of water consumption by plants. This simple method of calculation and comparison
between the real and theoretical ETM or ETP profiles allows the quantitative
discussion: 1) on the role of the soil microstructure behavior on the root
growing and, 2) on the realism of the crop coefficient taken into account in
the ETP or ETM estimation. In these coastal marsh fields, it also argues on the
difficulty of management facing to the water and/or salt stresses.