Comparative Study on Major Quality Parameters of Locally Produced Organic Fertilizers

Abstract

Population growth and changing lifestyles have led to a steady increase in the generation of municipal, industrial, and agricultural wastes, posing a significant environmental challenge. Composting offers a promising solution that is both economically and environmentally beneficial. To effectively implement this approach, it is crucial to focus on the quality of the feedstock and the production of high quality compost that meets established standards. This study examined the physicochemical characteristics of three different feedstock materials: municipal solid waste (MSW), sugar cane filtercake (FK), and poultry waste (PW), as well as their corresponding composts. The compost samples were also analyzed for their phytotoxicity. The aim was to compare the properties of these materials and evaluate their compliance with international standards for agricultural applications. In May 2023, composite samples were collected from three composting facilities: the Bishoftu municipal solid waste composting facility, the Metehara sugar factory compost yard, and the Bishoftu poultry waste composting. Representative samples were obtained by taking 10 sub-samples from various locations and depths of the compost/feedstock piles. These sub-samples were then thoroughly mixed to create 6 composite samples for each feedstock and its corresponding compost. The samples were dried, then crushed and sieved through 1.00 mm and 0.4 mm meshes. The physicochemical properties and phytotoxicity of the raw feedstocks and composts were evaluated using appropriate analytical methods. The ANOVA analysis revealed significant variations among the feedstocks. PW exhibited the highest electrical conductivity (7.48 dS/m ±1.18), organic carbon (36.12% ± 1.09), total nitrogen (3.37% ± 0.02), and total phosphorus (2.18% ± 0.27) content. MSW had the highest magnesium content (18.18 meq/100g). The physicochemical analysis and phytototcity test of the composts prepared from municipal solid waste (MSW), sugar cane filtercake (FK), and poultry waste (PW) also showed significant differences. PWC had the lowest pH (5.31 ± 0.15), the highest organic matter (64.43%±0.46) and the highest total nitrogen (3.54% ± 0.01). FKC exhibited the highest: pH (8.12±0.15), electrical conductivity (9.01ds/m ±0.15) and potassium (6.32% ± 0.11). MSWC had the lowest total Phosphorus (0.56 % ± 0.00634) and potassium content (0.62 % ± 0.04). The analysis of heavy metals in the compost showed that PWC had the highest concentrations of copper (103.74mg/kg±1.44) and zinc (783.11 mg/kg±7.92), while FKC showed the highest Mn content (935.47mg/kg± 4.82).MSWC had the highest Fe content (20,977.17mg/kg±143.55)and Ni content (38.10 mg/kg ±0.97). The highest germination index (GI) values of tomato were (85.51% ± 12.93) for PWC, and the highest germination index (GI) values of cabbage were (86.67%±5.20) for MSWC. Comparison with the international standards depicts that moderate to no phytotoxicity, which may support suitable seed germination and plant growth. In conclusion, the analysis of feedstock properties and compost quality provides valuable insights into the distinct compositions. Significant differences between compost samples highlight the need for careful selection of feedstock materials, optimizing feedstock blends to enhance compost quality, and application based on soil and plant requirements. Heavy metal concerns require developing robust quality assurance protocols and potential remediation to ensure compost safety and suitability.