SMART LYSIMETER: AN AUTONOMOUS, LOW-COST, AND PORTABLE LYSIMETER FOR USE IN A GREENHOUSE

Abstract

A lysimeter was designed, constructed, and tested to meet the needs of the University of Arizona’s Department of Biosystems Engineering to have an autonomous, low-cost, and portable lysimeter to be used in a greenhouse. Our lysimeter, the Smart Lysimeter can collect a control sample of nutrient solution and nutrient solution that drained from the plants and analyze it via various sensors to determine pH, electric conductivity data, and the drainage rate. The collected liquid is eventually pumped out of the system to a drainage channel to allow for recycling. This unit fills a market niche in that it automates common greenhouse management tasks and allows the greenhouse operator to make real-time operational decisions, without high-tech, expensive equipment, or strenuous manual labor. Furthermore, the Smart Lysimeter’s versatility allows it to be transferred between greenhouses and between crops with just a few simple steps. The design consists of a divided collection tank that houses the sensors, pumps, circuitry, and provides a place for the nutrient solution to be held for data collection. A Raspberry Pi serves as the microcontroller which features an LCD screen that allows the greenhouse operator to interact with the user interface, view current data, and review a historical log of data. The software developed for this system ensures that the data collection is autonomous and, on a user-defined time basis.