Calibration and Testing of Electrodes for Use in a Fertigation Monitoring System

EXECUTIVE SUMMARY Calibration and Testing Electrodes for Use in a Fertigation System Jack Hattaway 8/3/2016 Professional Master’s Degree Program California State University at San Marcos The Fertigation Monitoring System (FERM-SYS) is designed to continuously monitor nutrient concentrations, total ionic strength, temperature, and redox potential of the conditioned water delivered to plants by the multi-stage irrigation system at Dramm and Echter, a commercial nursery in Encinitas, CA. The goal of FERM-SYS is to implement the modern concept of precision agriculture to maximize the efficiency of nutrient delivery to plants, reduce diseases affecting the plants, limit excess fertilizer pollution to the surrounding water tables, and conserve water used by the crops. A prototype of the FERM-SYS is currently being installed at Dramm & Echter to monitor the fertigation system. The goal of this project is to calibrate the different electrodes off-line from the continuous nutrient monitoring system, and to monitor the water characteristics in the many different environments in the greenhouse. This knowledge will help to understand the long term measuring characteristics of the electrodes in different aqueous environments (different water stages in a greenhouse) over time and help to determine where the FERM-SYS should be installed in the irrigation system. This information will be used as a control for the in-line placement of the electrodes in the real-time continuous monitoring of the conditioned water in the irrigation system for the entire greenhouse. pH, redox, and nitrate probes will be calibrated and tested against standards for several months. After the probes are successfully calibrated, measurements will be analyzed for accuracy, precision and drift. The calibrated probes are then to be used to monitor water at the different stages in the irrigation system. The study will give a clearer understanding to the grower how water sources at Dramm & Echter interact with each other, and clarify what new processes the company might implement to improve the formulation of their fertilizer solutions. Dramm & Echter is one of the top producers of roses and gerberas. The project is being completed under the supervision of Dr. Geoffrey Landis. Future studies will include calibrating and testing a potassium ion selective probe and an electroconductivity probe for the system. These probes will be calibrated as describe herein and tested using the water at Dramm & Echter. Thereafter, these probes can be integrated into the system and real-time monitoring at Dramm & Echter can begin.