Bioconversion of Spent Mushroom Substrate and Arecanut Husk into Organic Manure and Its Effect on the Growth of French Bean (Phaseolus vulgaris L.)

Abstract

The present study investigated the bioconversion of spent mushroom substrate (SMS) and arecanut husk (AH) into nutrient-rich organic manure using microbial decomposers. Considering the large quantities of SMS and AH generated annually and their slow degradability, the research aimed to develop an eco-friendly method to manage these agro-industrial residues while improving soil fertility. Proximate analysis of SMS and AH revealed high carbon content with a wide C:N ratio and low nutrient levels, indicating the need for microbial intervention. Composting experiments under greenhouse conditions employed various combinations of AH and SMS (90:10, 80:20, 70:30 and 100 %) enriched with microbial decomposers (Paenibacillus mucilaginosus, Bacillus subtilis and Pleurotus ostreatus) along with urea, gliricidia and rock phosphate. Among the treatments, 70 % + 30 % SMS (T5) produced well-decomposed compost that met the quality standards for organic manure (FCO, 1985). Pot culture experiments on French bean (Phaseolus vulgaris L.) demonstrated that integration of organic manure with recommended NPK doses, particularly at 125 % OM (T6), significantly enhanced plant growth, leaf area and soil biological fertility. The study concludes that co-composting AH and SMS using microbial decomposers is an effective, economically viable and environmentally sustainable method for producing high-quality organic manure, promoting plant growth and improving soil health.