Capacitive soil moisture sensor

The utility model discloses a novel capacitive soil moisture sensor using a Hartley three-point oscillating circuit. The capacitive soil moisture sensor comprises a detection module, a reference frequency signal generating circuit, a frequency conversion circuit, a frequency computing circuit and a power supply, wherein the detection module and the reference frequency signal generating circuit are respectively connected with the frequency conversion circuit, and the frequency conversion circuit is connected with the frequency computing circuit; the detection module comprises a probe and a Hartley oscillating module which are connected, and the Hartley oscillating module comprises a Hartley oscillating circuit and a temperature compensation circuit; the frequency conversion circuit is used for receiving signals transmitted by the Hartley oscillating module and the reference frequency signal generating circuit, and the power supply supplies power to the above components. The capacitive soil moisture sensor provided by the utility model has the advantages of simple structure, reliable signal transmission and capability of avoiding interference; the Hartley three-point oscillating circuit and a temperature compensation design are adopted, so that the stable oscillation starting is realized; the pin type detection module hardly damages soil, and the measurement results are relatively accurate after the detection module is inserted into soil.