Attempts have been made by several scholars to review
soil moisture measuring techniques [8]–[12]. Through comparative
analysis of various methods and theories, we concluded
that the dielectric method was the most promising one. Among
the dielectric methods, capacitance method has unique advantages
compared with other dielectric methods, including (1) the
ability to measure dynamic conditions [13]; (2) low cost of the
measurement instruments and minimal site disturbance [14];
and (3) the adaptivity of the sensor geometry, facilitating the
development of a variety of configurations [15].