Determining the hydraulic properties of a Sahelian crusted soil. 1. In field experiment and measurements.

Surface sealing affects considerably the infiltration capacity of soils in the Sahelian zone. Due to experimental constraints, in situ determination of the hydraulic resistance of soil crusts is seldom attempted. A methodology is presented that allowed the determination of the hydrodynamic characteristics of a ferrugineous soil located in Senegal and their evolution under two successive simulated rains. Values inferred from tensiometric and capacitive measurements are, to some extent, in agreement with those determined by tension disk infiltrometer at the end of the experiment; however, only the former method permits the assessment of the crust resistance. The structural modification of the soil surface is confirmed by mercury intrusion on undisturbed soil samples. ((C) Inra/Elsevier, Paris.)