Biodegradable Index and Earthworm Population in Vermicompost: Influence of Substrates, Composting Period and Rock Phosphate Enrichment

Abstract

Vermicomposting is a sustainable technique for converting organic waste into high-quality vermicompost using earthworms. This study investigated the effects of different substrates, composting periods, and enrichment with rock phosphate on the biodegradable index (BI) and earthworm populations in vermicompost. The experiment was conducted at Madan Bharti Agricultural College, Agwanpur, Saharsa (Bihar), using agricultural wastes, cow dung, rock phosphate, and phosphate-solubilizing bacteria (PSB) in various treatment combinations. BI decreased with increasing days after sowing (DAS), with no significant change from 30 to 60 DAS, a significant decrease at 90 DAS, and a non-significant change at 120 DAS. The average BI values ranged from 5.43 to 4.80 for DAS 30-120 at 30-day intervals. The earthworm population increased with varying substrates and the application of rock phosphate and PSB, with a significant decrease from 30 to 120 DAS. The average earthworm population increased from 630 to 986 for DAS 30-120 at 30-day intervals. The results demonstrated that altering substrates and enriching vermicompost with rock phosphate and PSB influenced its characteristics, leading to the disintegration of organic debris and interactions between bacteria and earthworms. The BI values suggested that inoculation substrates matured, reaching a value of 2.71 in the humification phase. This study highlighted the importance of appropriate organic substrates for earthworm growth and reproductive performance, which are significantly influenced by substrate quality, temperature, and moisture content.