Jinghui Xu
College of Water Resources and Architectural Engineering, Northwest A&F University

Thermal-time domain reflectometry (T-TDR) is a new probe which was developed to simultaneously measure soil water content , bulk electrical conductivity , thermal conductivity , heat capacity , and thermal diffusivity .TDR was used to measure and , and the heat pulse (HP) method was used to determine. In recent years, it have been be improved for vadose zone measurements, determining soil bulk density and soil water evaporation measurement. T-TDR has many functions but the measurement accuracy should be improved because the needle of probe is too short for TDR measurement. A new Thermo-FDR probe design and some new ways will be talked about to improve the measurement accuracy.