IDENTIFICATION FOR ION-BASED FERTIGATION CONTROL IN SOILLESS GREENHOUSE CULTIVATION

摘要

Progress in instrumentation and the need for quality control stimulate the rethinking of irrigation and fertilisation (fertigation) of crops in greenhouses. Feedback control using ion specific electrodes in the drain offers opportunities for automatic demand satisfaction. The fertigation system is characterised by pulse-wise water supply, which puts unconventional challenges to the measurement system. Limitations from practice require identification and control design procedures to be robust and simple. This paper introduces a reduced model for the system and describes the practical identification of the nutrient dynamics in a measurement gully on a time scale that is relevant to the crop.