TDR soil moisture data measured in different soils

Long series of soil moisture data have been collected during some field experiments using the Time Domain Reflectometry (TDR) technique. The time evolution of the soil moisture profile highlights features of the different soil physics characteristics. Among the soil considered, a sand shows the presence of an inflection point in the soil moisture profile whereas this has not been observed in a silty loam of a sub-alpine valley. Under suitable assumptions the cumulative evaporation has been obtained by the measured soil water content and precipitation data computing the mass balance of a soil column. Assuming the desorption approximation, the cumulative evaporation has been obtained and a set of diffusivity values have been estimated. The presence of a daily oscillation in the TDR data is evident in all the data records. The amplitude of the oscillation depends on the depth. The influence of the soil temperature and of the instrument temperature on the TDR data has been studied carrying out laboratory measurements. They appear to be of the same order of magnitude, about –0.1 % °C. 1 Osservatorio Geofisico Dipartimento Ingegneria Materiali e Ambiente Universita di Modena e Reggio Emilia Via Campi 213/A I-41100 MODENA (Italy) Tel: +39 059 2055328 Fax: +39 059 373180 marilena.menziani@unimo.it