An open source controlled environment agriculture platform : exploration of root zone temperature effects and thermal management

Abstract

A first prototype of a GRObot open source controlled environment agriculture platform was built with air and water temperature control systems. Caesar basil seedlings were grown in the GRObot with a shallow water culture hydroponic system for two-week periods. In the first trial, the root zone temperature (RZT) was allowed to fluctuate with the air temperature resulting in an average RZT of 22.7°C, and in the second trial, the RZT was chilled to an average temperature of 20.5°C. For both trials, the air temperature was controlled to mimic a warm climate, with set temperatures of 300°C during the daytime and 25°C at night. The basil in the chilled RZT condition exhibited poor growth, while the basil in the fluctuating RZT condition exhibited the exponential growth expected of healthy seedlings. Temperature data recorded throughout these trials were used to construct a steady state thermal model of GRObot operation. Using this model, an interactive applet was created as a tool to help GRObot users predict electricity costs for environmental control with different environmental recipes to within two cents. This research demonstrates the first experiment aimed at determination of a crop's environmental recipe using the GRObot open source controlled environment platform.