Agronomic evaluation of Tenebrio molitor frass as an organic fertilizer for Chinese cabbage cultivation

Purpose: As the insect farming industry expands, increasing amounts of insect frass are generated, highlighting the need to evaluate its potential as a safe and effective fertilizer resource.This study evaluated the physicochemical characteristics, fertilizer value, and agronomic potential of Tenebrio molitor frass as a by-product fertilizer for Chinese cabbage cultivation.Methods: The physicochemical properties, compost maturity, and heavy metal contents of T. molitor frass were analyzed.The effects of T. molitor fee on Chinese cabbage growth, yield, and post-harvest soil chemical properties were evaluated through a field experiment with four treatments: Control (no organic amendment), Compost, Frass-S (190 kg 10a -1 ), and Frass-D (380 kg 10a -1 ).Results: T. molitor frass contained 77.1% organic matter, 4.14% total nitrogen (T-N), 3.29% P 2 O 5 , and 2.57% K 2 O, with all heavy metal concentrations remaining below the limits specified by the Korean fertilizer standards.Both frass treatments significantly increased head weight, head height, and the numbers of outer and inner leaves, resulting in yield increases of 6.4% and 5.9%, respectively, compared with the Control.However, there was no different between Frass-S and Frass-D.After cultivation, soil organic matter increased from 16 g kg -1 in the Control to 18 and 20 g kg -1 in the Frass-S and Frass-D treatments, respectively.Exchangeable K and Mg also increased significantly, whereas soil pH, EC, available P 2 O 5 , and exchangeable Ca and Na were not significantly affected.Conclusions: T. molitor frass was found to be a safe and effective organic fertilizer resource that improved Chinese cabbage growth and soil fertility.The standard application rate (190 kg 10a -1 ) appears to be appropriate for Chinese cabbage cultivation.These results suggest that T. molitor frass has considerable potential as a by-product fertilizer for environmentally friendly organic agriculture.