An irrigation control system is described for optimizing water used for growing crops. The irrigation control system uses a moisture sensor to measure soil moisture by measuring directly the relative phase velocities of different modes of propagation along a metallic structure mounted to a dielectric substrate. The average phase velocity is a function of the water content of the soil. The water content measurement is then transmitted to a central controller which then, through a set of heuristic algorithms, regulates the water distributed to the soil in a spatial and temporal manner.
