The invention relates to a stable soil
hygrometer with a protection function. The stable soil
hygrometer comprises a main body and a probe, wherein the stable soil
hygrometer further comprises a triggering mechanism and at least two supporting mechanisms, each supporting mechanism comprises a sliding rod, a first spring, a sliding sleeve, a transmission rod, a connecting
pipe, a second screw rod and a positioning component, the positioning component comprises a supporting sleeve, a second spring and a supporting rod, the triggering mechanism comprises a guide rod, a driving component, a firstscrew rod, a moving block, a second gear, two contact switches and at least two triggering components, and each triggering component comprises a bracket, an
electromagnet and a permanent
magnet. In the stable soil hygrometer with the protection function, via the supporting of the supporting mechanisms on the main body, the stability of the soil hygrometer is improved, when the probe of the soil hygrometer is placed in the soil for a long time, the supporting mechanisms can be triggered by the triggering mechanism, then the soil hygrometer is taken out of the soil through the supporting mechanisms, so that the probability of damage to the soil hygrometer is reduced.