Effect of Organic Substrates on Vermicompost and Compost Quality and Multiplication Rate of Earthworms

Abstract

Vermicomposting utilizes earthworms to recycle organic wastes from urban, industrial, and agricultural sources into valuable organic fertilizers. During vermicompost preparation, organic waste products are decomposed through the collaborative activity of beneficial microbes and earthworms. The present study aimed to investigate the effects of various organic substrates on the quality of vermicompost, compost, and the multiplication rate of earthworms. The organic waste substrates, water hyacinth, paddy straw, cow dung, and kitchen waste, were converted into nutrient-rich vermicompost using the earthworm species Eisenia fetida and compost through the composting process. The results indicated that the highest recovery percentage 54.20%, increased nitrogen content 1.80%, and the shortest maturation time was observed in treatment T1 (water hyacinth + paddy straw + cow dung @ 2:1:1). Higher phosphorus and potassium content were recorded in T4 treatment (WH+CD @ 3:1). However, the highest earthworm multiplication rate and the lowest bulk density of vermicompost were recorded in treatment T3 (paddy straw + cow dung @ 3:1).  The total N content across the organic substrates ranged from 0.67% to 2.20%. The highest total N content (2.20%) was recorded in KW, while the lowest (0.67%) was observed in CD. KW showed the highest level of total P (0.54%) content, followed by WH (0.49%), CD (0.40%), and PS (0.20%). The total K content was greatest in WH (3.68%), followed by KW (2.30%), PS (1.89%), and CD (1.29%). Furthermore, the total S content was highest in CD (0.72%), followed by KW (0.54%), WH (0.39%), and PS (0.36%). The organic substrates' carbon-to-nitrogen (C: N) ratio exhibited considerable variation, ranging from 18:1 to 49:1. The combinations of water hyacinth, paddy straw and cow dung, were found to be effective organic substrates for producing high-quality vermicompost.