A LOW-COST WATER DETECTION METHOD FOR FURROW IRRIGATION CONTROL

The typically low efficiency of furrow irrigation can be raised by a n ew control method, In this method, a computer monitors the water advan ce along the furrows during the initial phase of the irrigation, The d istance-versus-time data obtained are used to calculate the soil's inf iltration coefficients, which, in turn, are used in the water infiltra tion model, The computer can thus determine the most appropriate mater input rate and application time to achieve maximum efficiency, This p aper describes a simple low-cost water sensing network that enables a computer to monitor the water advance in real-time, Each sensing netwo rk 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 oscill ation 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 nonte chnical people with minimal tools.