An irrigation control valve has two movable members that can independently
or in combination block the flow of water in a conduit, or be fully
retracted of at some point in-between. A moisture sensitive element is
arranged to be placed in contact with the soil and expands or retracts
dependent on the moisture within soil adjacent the moisture sensitive
element. The moisture sensitive element is connected or coupled to a
moisture controlled member. Dependent on the moisture of the soil
adjacent the moisture sensitive element, the moisture controlled member
is moved further into the conduit with increasing moisture in the soil.
The moisture controlled member and an electronically controlled member
are located adjacent each other at the conduit. The electronically
controlled member determines how far the moisture controlled member needs
to move in order to fully block the flow of water in the conduit. An
electronic controller is operable to determine the achieved level of
moisture in the soil, by means of the electronically controlled actuator
and the electronically controlled member.