Calibração de equipamento de TDR em condições de laboratório e campo para dois tipos de tubos de acesso

Abstract

The time domain reflectometry (TDR) stands out amongst the techniques used for the measurement of the water content in the soil due to characteristics such as high precision, conservation of the soil’s physical structure, easiness of use and portability. However, due to the high cost of equipment and access tubes and the need to calibrate, its application has been limited to research. Thus, the aim of this work was to calibrate the TDR, in laboratory and field conditions, using TECANAT and PVC access tubes. The results in the laboratory were satisfactory for all calibrations in the two types of tubes, with the TDR reading representative for estimating the moisture of the Typic Haplustept. The field results were reasonable for calibration of the dielectric constant in the two tubes studied in Typic Kandiudult, due to environmental factors, from clayey texture of soil and adherence of the tube to the soil. The use of TECANAT and PVC tubes requires calibrations for each soil, being that the viability of its use still depends on the quality of its installation in the soil.