Estimation de la conductivité thermique d'un sol in situ, à l'aide d'une sonde à choc thermique

Abstract

sol / conductivité thermique / in situ / sonde à choc thermique / méthode de mesure Summary — Estimating thermal conductivity of soil in situ, with a new thermal probe. A simple system, using a thermal probe was designed to measure the thermal conductivity of a soil in situ. The operating conditions were investigated. The system was shown to be quite adapted for the field experiments. Measurements were made in a siltyclay-loam soil for different humidity and density conditions. As expected, the thermal conductivity increased with gravimetric water content and density of the soil. In the deeper layers, with homogeneous and larger densities, the thermal conductivity had high, steady values even at low water content, which may be due to the shrinkage of clay as the soil dries, compensating the diminution of thermal conductivity due to water losses. This behavior was quite different from that of the tilled surface layers with a granular structure. The measured values of thermal conductivity were higher than those found by laboratory methods using reconstituted soil samples. The absence of a reference method for in situ determination of the thermal conductivity did not allow us to completely validate this thermal probe.soil / thermal conductivity / in situ / thermal probe / measuring method

Effect of tillage on bare soil energy balance and thermal regime: an experimental study

“…Soil compaction greatly increased thermal conductivity (about 200 % at 0.05 m deep), and gave a smaller increase in heat capacity (about 20 % at 0.05 m deep), as observed by Allmaras et al [3]. This confirms the great effect of soil bulk density on changes in thermal conductivity, as measured by Bussière et al [6] using thermal probes. The timing of the secondary tillage had a smaller effect on thermal conductivity than did soil compaction.…”

“…Evaporation depends on the vapour saturation deficit above the soil surface, the aerodynamic resistance to water vapour transfer (r a ) and the soil resistance to water transfer (r s ) (equation (6)). …”