DESIGN AND EVALUATION OF A CONTROL SYSTEM FOR THE FERTIGATION DEVICE

In view of low automation control and unstable output fertilizer solution concentrations of solid fertilizer applicators, a control system based on a single-chip microcomputer and fuzzy control was proposed and introduced into a fertigation device. The control system calculated and adjusted the fertilizer-feeding flow rate according to the input and feedback information, resulting in the automatic operation of the fertigation device. It can also detect the output fertilizer concentration in real time. Experiments were conducted to test the adjustment and detection accuracy of the control system and to investigate its performance. Adjustment and detection errors were below 5% when the inlet water flow rate, the fertilizer-feeding flow rate, and the fertilizer concentration were 0.2 to 1.5 m(3)/h, 1 to 50 kg/h, and 1 to 14 g/L, respectively. The time the output fertilizer reached the set concentration was around 5 minutes and was far shorter than the fertigation device without a control system. The fertilizer concentration deviation decreased by about 20% after accessing the control system for the fertigation device. Under the control system, the fertigation device can discharge fertilizer with a variable concentration, and the fertilization deviation was about 5%. Therefore, the control system not only made automatic operation and variable concentration fertilization of the fertigation device to be achieved but also improved the fertilization performance of the fertigation device.