A system for detecting the absence of a thin nutrient film in a plant growing trough includes a trough for use in a thin-nutrient-film agricultural system, the trough having a trough base across which the thin-nutrient-film passes. A high frequency RFID tag, located in or below the trough base, is operable to receive an interrogator signal and to transmit an authentication signal. When an RFID reader passes over the RFID tag and transmits an interrogator signal, an authentication signal is generated only in the absence of a shielding layer of nutrient film, thereby indicating a failure of the nutrient film circulatory system.
