Résumé
This study evaluates the effect of homemade dry manure tea (HMT), a liquid organic fertilizer widely used in North Africa as an alternative to synthetic fertilizers. The main objective is to characterize a specific HMT formulation and to study its effect on spinach growth at two different doses as compared with a synthetic fertilizer. HMT was applied to a spinach crop under controlled conditions in comparison with a synthetic fertilizer, applied at equivalent concentrations of nitrogen (N), phosphorus (P) and potassium (K). The effects of both types of fertilizer were evaluated, focusing on plant biomass, leaf morphology and nutrient uptake. The results show that the dosage of HMT typically used in Tunisia produces effects comparable to those of a synthetic fertilizer on spinach biomass, leaf morphology and aerial potassium uptake. However, a dose of HMT that was six times more concentrated in N, P and K than the farmers’ dose resulted in inhibitory effects on biomass and leaf morphology, that were not observed with the equivalent high dose of synthetic fertilizer. The use of HMT at farmer’s doses could provide a viable, locally sourced and environmentally friendly alternative to synthetic fertilizers. However, future research should focus on characterizing the variability of HMT based on its preparation methods, as this variability could significantly influence the composition of HMT and consequently its effects on crops.