Design and implementation of a low-cost sensor network to monitor environmental and agronomic variables in a plant factory

Monitoring equipment for plant-factory automation requires big capital investments. Low-cost open-source microcontroller platforms have been employed in agriculture to monitor and control different variables of importance for crop production. A low-cost plant-factory monitoring system for measuring air temperature, relative humidity, plant-leaf temperature, pH, electrical conductivity, dissolved oxygen and temperature of the nutrient solution is presented here. All the information is recorded in a micro SD memory and can be accessed by Bluetooth in real-time. The developed system was tested during a cycle of a lettuce crop in a research plant-factory facility. The quality of the collected data was evaluated and compared with a well-known research-grade monitoring system. The low-cost sensors showed an easy to correct bias when were compared to those of research-grade, with a correlation coefficient over 0.96. The results showed that low-cost systems, like the one implemented here, are a good alternative for monitoring environmental and physiological variables in controlled environmental agriculture facilities.