Bioconversion of Agricultural Residues into Nutrient-Enriched Biofertilizers Using Trichoderma sp.: Effects of Substrate Type and Incubation Time

Improper disposal or open burning of agricultural waste releases smoke, particulate matter, and greenhouse gases, contributing to air pollution and climate change. The utilization of agricultural wastes as substrates for biofertilizer production offers a sustainable approach to waste valorization and nutrient recycling. This study evaluated the effects of agricultural waste type and contact time on the nutrient composition of Trichoderma sp.-based biofertilizer produced from sawdust, rice husk, and guinea corn husk. A factorial experiment was conducted using four substrates and four incubation periods (0, 5, 10, and 15 days). Nutrient parameters, including total nitrogen (TN %), phosphorus (P %), and potassium (K %), were determined and subjected to analysis of variance. The biofertilizer exhibited high microbial viability, with a highest propagule density of 6.46 × 1011 CFU ml−1, indicating successful fungal colonization. Significant (p < 0.0001) effects of substrate type, contact time, and their interaction were observed for all nutrient parameter accumulation. Total nitrogen increased with incubation time, reaching a maximum of 0.901% in guinea corn husk after 15 days. Rice husk recorded the highest phosphorus concentration (2.497%) at 15 days, while sawdust produced the greatest potassium concentration (2.389%) at 15 days. The results indicate that Trichoderma sp. effectively bio-converts agricultural residues into nutrient-rich biofertilizers, with substrate type influencing nutrient profiles. This technology represents a promising strategy for sustainable soil fertility management and circular agricultural production systems, depending on substrate type used and incubation time.