Automatic watering system control - has probe shielded by tunnel, with solenoid valve control circuit completed when moisture content increases to min. conduction level

摘要

The watering of an area of ground is controlled as a function of the conductivity of the soil beneath a tunnel. The sides of the tunnel are embedded sufficiently deeply in the ground to ensure that moisture reaches the soil below the tunnel only through capillary action from the soil at either end of the tunnel. Wires (L) are connected in circuit with a clock switch and a solenoid valve of the watering apparatus. When the soil beneath the tunnel is sufficiently damp to allow a current to flow between the wires (L) through the soil, the solenoid valve is closed and watering stops.