Effet du frass de Hermetia illucens L. sur la croissance et le rendement de l’amarante (Amaranthus viridis L.) cultivée à Kinshasa, Republique Démocratique du Congo

Abstract

The use of local and sustainable organic fertilizers is a priority for improving market-gardening productivity in tropical environments. This study aimed to assess the effects of different doses of Hermetia illucens L. frass on the growth and yield of amaranth under the pedoclimatic conditions of Kinshasa. The experiment was set up in a randomized complete block design with seven treatments: T0 (unfertilized control); T1 (urea 46% N); T2 (poultry manure); T3 (frass 25%); T4 (frass 50%); T5 (frass 75%); and T6 (frass 100%). Measured parameters included plant height, collar diameter, leaf count, leaf length and width, branch number, and fresh biomass yield. Results revealed highly significant effects of fertilizer and time on all variables (p < 0.001), with growth increasing proportionally with frass dose. At the fourth week, treatment T6 recorded the highest values: plant height 26.9 cm, 22 leaves per plant and yield 41.8 t/ha, significantly higher than the control T0 (21.1 t/ha) and all other treatments (p < 0.001). Collar diameter and leaf length followed different dynamics, with conventional treatments showing greater values at the end of the observation period. Frass applied at 100% dose proved the most effective fertilizer for enhancing vegetative growth and amaranth yield. It thus represents a promising, sustainable, and economically viable alternative to mineral fertilizers and animal manure for urban market gardening in Kinshasa.