Résumé
1. Introduction In the current agricultural landscape, the intensive use of synthetic fertilizers to meet the nutritional needs of crops, such as spinach, presents significant environmental and economic challenges. Historically, various cultures, especially in North African countries, have turned to organic methods like homemade manure tea (HMT) (Azeez et al., 2014). This tea, obtained by infusing manure in water, is known to facilitate the decomposition of organic matter and enhance nutrient release (Leauthaud et al., 2022). Although anecdotal accounts praise the benefits of HMT in terms of plant growth and soil quality improvement, there remains a lack of empirical studies validating these claims. The quantity and quality of nutrients provided by these teas are not well-documented (Eudoxie and Martin, 2019). Given these gaps, this study aimed to assess the impact of HMT on spinach biomass and leaf metrics in comparison to a synthetic fertilizer with equivalent concentrations of nitrogen (N), phosphorus (P), and potassium (K). Spinach (Spinacia oleraceae L.) was chosen due to its rapid growth rate, high nitrogen demand for optimal development, and its significant agronomic and nutritional importance (Pandjaitan et al., 2012; El-Saady, 2016). 2. Materials and Methods The study focused on preparing Homemade Dry Manure Tea (HMT) using a popular North African technique before cultivating Lazio spinach in soil from Cazevieille, France, employing a completely randomized experimental design with five distinct treatments. Treatments T1 and T2 varied HMT dosages, with T1 being a lower typical dose and T2 six times the NPK content of T1. Three control treatments were also established: W (water only), S1, and S2, involving synthetic fertilizers designed to match the nutrient concentrations of HMT doses. The spinach was grown under controlled conditions for 41 days before harvest. Measurements included leaf count and dimensions, stem and petiole lengths, and both fresh and dry biomass weights. Chemical analysis of the aerial parts was conducted to assess nutrient content. 3. Results and Discussion In our study examining the impact of homemade dry manure tea on the growth, morphology, and nutrient uptake of spinach, we observed that the use of a peasant dose of HMT resulted in a dry biomass comparable to that of a synthetic fertilizer with the same NPK concentration. This finding suggests that HMT, when used in modest amounts, could emerge as a viable alternative to synthetic fertilizers. Plants treated with T1 and S1 dosages displayed leaves noticeably longer and broader than those in the W control group. However, the plant roots did not exhibit significant variations in dry biomass between the different treatments. Our analysis also disclosed heightened potassium absorption in plants subjected to the T1 and S1 treatments, compared to the W control group. This revelation is in line with previous studies highlighting the positive influence of increased potassium intake on the growth and yield of various plants. Nonetheless, observations related to the T2 treatment raised concerns. Indeed, plants exposed to this treatment showed a significant decline in dry biomass, morphological measurements, and nutrient uptake. This trend suggests that high doses of HMT might contain components toxic to spinach. Moreover, the high salinity in HMT could play a pivotal role in the observed toxicity in the T2 treatment. It is also conceivable that other factors, such as micronutrient imbalances, or even microbial effects, are influencing these outcomes.