Evaluation of the Heat-Pulse Technique for Measuring Soil Water Content with Thermo-TDR Sensor

The heat-pulse technique is emerging as a useful technique for measuring soil water content, (with the advantages of automated, rapid, and minimal destructive. The purpose of this study is to evaluate the performance of the Liu et al. (2008) thermo-TDR (time domain reflectometry) sensor for measuring soil water content using the heat-pulse technique. For this sensor, the root mean square errors (RMSE) of heat-pulse soil water content HP) estimates compared with gravimetric measures in laboratory evaluations was 0.011 m3 m-3 and was 0.018 m3 m-3 in a field evaluation. The results indicated that the sensor with a needle diameter of 2 mm, needle length of 40 mm, and needle-to-needle spacing of 8 mm can provide accurate, nondestructive, repeated estimates of soil