A low-cost water detection method for furrow irrigation control

The typically low efficiency of furrow irrigation can be raised by a new control method. In this method, a computer monitors the water advance along the furrows during the initial phase of the irrigation. The distance-versus-tine data obtained are used to calculate the soil´s infiltration coefficients, which, in turn, are used in the water infiltration model. The computer can thus determine the most appropriate water input rate and application time to achieve maximum efficiency. This paper describes a simple low-cost water sensing network that enables a computer to monitor the water advance in real-time. Each sensing network consists of up to 14 water detectors linked by a maximum of 1000 m of inexpensive twin-wire. The detection of water is done by the change in capacitance of a wire element. This alters the frequency of oscillation of a relaxation oscillator. The detectors signal their states to the computer by means of current pulses generated from the oscillator. The simplicity of the network allows easy field maintenance by nontechnical people with minimal tools