Production of Bio-Fertilizer Grade Derived from Biochar and Agricultural By-Product

Abstract

Methods that are cost-effective for making organic fertilizers from agricultural waste which is locally available obstruct the development of environmentally sound farming practices. This study developed a complementary nitrogen, phosphorus, and potassium (NPK) biochar-based fertilizer using four materials that are locally available: chicken manure, bone meal, banana peel, and biochar made from black currant leaves. The materials were examined using proximate and ultimate analyses as well as BET, SEM-EDX, and ED-XRF techniques in order to evaluate their suitability as sources of nutrients and as soil conditioners. The carbonization of the black currant leaves yielded a mesoporous biochar having a BET surface area of 140.06 m²/g, a micropore volume of 0.122 cm³/g, and a pore diameter of 3.02 nm, thus confirming its effectiveness as a nutrient-retention agent. Once more, the ultimate analysis of chicken manure revealed it to have the highest nitrogen content (20.25%), while bone meal was found to have a high phosphorus content (26.0% P₂O₅ according to ED-XRF) and high calcium levels (73.92% Ca according to SEM-EDX). Furthermore, banana peels are rich in potassium, with 71.0% K₂O as determined by ED-XRF analysis. A mixture of 2000 g was prepared consisting of 1000 g of chicken manure, 500 g of bone meal, 200 g of banana peel, and 300 g of biochar, the amount of biochar being deliberately set at 15% of the total mass in order to act as a soil enhancer and as a medium for nutrient retention. The NPK composition of the resulting product was 2.4:5.1:2.1, an indication of the high nutrient density of the feedstocks chosen and showing that the fertilizer is appropriate for use with phosphorus-demanding crops such as legumes, tubers, and fruiting plants during their flowering phases. The study shows that it is feasible to turn agricultural waste into an environmentally friendly NPK bio-fertilizer and helps to improve crop productivity.