THE TEMPERATURE CORRECTION FOR THE ELECTRICAL RESISTIVITY MEASUREMENTS IN UNDISTURBED SOIL SAMPLES: ANALYSIS OF THE EXISTING CONVERSION MODELS AND PROPOSAL OF A NEW MODEL

One of the challenges in soil science is to understand the relationships between electrical resistivity and other soil properties. Indeed, electrical resistivity is a complex soil electrical property that is affected by various soil parameters that can interact. Soil temperature plays a central role among all of the factors that significantly influence electrical conductivity. To determine the effect of the other soil parameters, the effect of temperature is commonly corrected on the experimental data using conversion models. These models have been developed from specific experimental data (usually measurements on soil solutions) but are extensively used not only on solutions, but also on disturbed or undisturbed samples or even on field experiments. We review several existing conversion models described in the literature and test their limits of validity on results of laboratory experiments on undisturbed soil samples at various water contents, clay contents, and temperatures. Our study shows that the models are reliable for correction of the effect of temperature when the volumetric soil water content is high, that is, near saturation. To better correct the temperature influence on the electrical resistivity measured on undisturbed soil samples with varying water content or clay content, a new conversion model dependent on only one parameter was developed. This useful tool still has to be confirmed over a large range of soils and for temperatures greater than 20 degrees C. (Soil Science 2008;173:707-720)