Abstract: A sensor device is shown for detection of soil moisture levels using thermal diffusivity techniques. The sensor device has a porous media in a first zone, a heated temperature sensor arranged within the first zone, a second zone of a thermally conductive dense media containing a second reference temperature sensor, and leads connecting the sensors to a circuit to provide power to the heated temperature sensor and to the second reference temperature sensor. The circuit includes a comparator to compare outputs from the heated temperature sensor to the second reference temperature sensor so as to provide a signal indicative of soil moisture levels when the sensor device is operationally placed to receive soil moisture into the first zone.

Abstract: An irrigation control system includes a soil moisture sensor (S) that controls the common lines of various irrigation valves (VA) being controlled by a conventional irrigation time based controller (TC). The sensor is in a first zone of primarily shallow rooted plants. A timer (TR) is activated whenever the soil moisture sensor allows the first zone to be watered. The timer (TR) increments a counter (CR) which closes after a pre-set number of irrigation cycles of the first zone having been completed. When the counter (CR) close contacts (C), then the irrigation valves feeding a second zone of primarily deep rooted plants are activated.

Abstract: The invention relates to a device adapted to reliably operate solenoids controlling valves at long distances from a central control station thereby enabling the use of light weight electrical cable between the control station and the solenoid, the device including a capacitor and a switching arrangement enabling current stored by the capacitor to be supplied to the solenoid to activate the solenoid, power being supplied to the capacitor from the central control station.

Abstract: A moisture sensing element is provided and is constructed of a body having therein a first zone formed of porous material with a first range of pore size having a first mean pore size and a second zone formed of a porous material with a second range of pore size having a second mean pore size such that in use the body is located within a desired soil area under surveillance whereby both the first and second zones are placed in hydraulic conduction with the desired soil area. The first mean pore size is substantially greater than the second mean pore size such that the second zone will remain hydrated when the first zone is becoming dehydrated. Electrode elements are associated with each of the first and second zones in spaced relation and define therebetween respective electric current flow paths through each of the first and second zones for sensing an electrical property of each of the zones.