Capacitance type soil moisture sensor

The utility model relates to a capacitance type soil moisture sensor which is provided with two poles of a capacitor, wherein conducting wires of the two poles are connected with a signaling conversion circuit. The utility model is characterized in that a stainless steel bar with a helical groove port is wound with an enamelled wire, the stainless steel bar is used as one pole and the enamelled wire is used as the other pole. A clay pipe chamber is arranged outside a core of the stainless steel sensor, and the clay pipe chamber is loaded with light loam which is treated by artificial structure modifying agents. In a prioritization proposal, the artificial structure modifying agents adopt polyacrylamide which takes 0.1 % of the weight of the loam. The light loam which is treated by the artificial structure modifying agents has the components: 8 to 10% of clay particles which are smaller than 0.001 mm, 70 to 72% of powder particles which are between 0.001 mm and 0.05 mm, and 19 to 21% of fine sand particles which are larger than 0.05 mm, and the particles are fixed by high molecular polymers. The utility model makes the sensor kept favorable hydraulic connection with outside soil, rating work between the capacitance content of the sensor and the moisture content of the soil is simplified and the utility model solves a difficult problem in the traditional technology.