Organic waste recycling by vermicomposting amended with rock phosphate impacts the stability and maturity indices of vermicompost

ABSTRACT

Recycling organic waste can help the land be nourished, properly disposed of, and protected from the negative impacts of chemical fertilizers. Organic additions like vermicompost can help restore and preserve the quality of the soil, however, producing vermicompost of a high enough standard is difficult. This study was planned to prepare vermicompost by utilizing two different organic wastes viz. household waste and organic residue amended with rock phosphate and further evaluate their stability and maturity indices during vermicomposting for quality of produce. For this study, the organic wastes were collected and vermicompost was prepared by using earthworm (Eisenia fetida) and with or without enriching with rock phosphate. Results showed that pH, bulk density, and biodegradability index were decreased and water holding capacity and cation exchange capacity was increased with the gradual progress of composting starting from 30 to 120 days of sampling/composting (DAS). Initially (upto 30 DAS) water-soluble carbon and water-soluble carbohydrate increased with rock phosphate enrichment. The population of the earthworms and enzymatic activities (CO₂ evolution, dehydrogenase, and alkaline phosphatase) were also increased on enriching with rock phosphate and with the progression of the composting period. Rock phosphate addition (enrichment) also reflected the higher content of phosphorus (106% and 120% for household waste and organic residue, respectively) in the final product of vermicompost. The vermicompost prepared from household waste and enriched with rock phosphate showed greater maturity and stability indices. Overall, this can be concluded that the maturity and stability of vermicompost depend on the substrate used and improves on enriching with rock phosphate.

Implications: Our study concludes that the quality of vermicompost depends on different substrates, composting period, and enrichment with rock phosphate. The qualities of vermicompost were best found under household waste-based vermicompost enriched with rock phosphate. The efficiency of vermicomposting process using earthworms was found maximum for enriched and without enriched household-based vermicompost. The study also indicated that several stability and maturity indices are influenced by different parameters and hence cannot be determined by a single parameter. The addition of rock phosphate increased the cation exchange capacity, phosphorus content, and alkaline phosphatase. Nitrogen, zinc, manganese, dehydrogenase, and alkaline phosphatase were found higher under household waste-based vermicompost relative to organic residue-based vermicompost. All four substrates promoted earthworm growth and reproduction in vermicompost.

Acknowledgment

The authors are thankful to the Director of Research, and Head of the Soil Science and Vermicompost unit, RPCAU, Pusa, for providing research laboratory facilities for sample analysis.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The authors confirm that the data supporting the findings of this study are available within the article.

Nomenclature

BD	=	Bulk density
BI	=	Biodegradability index
CEC	=	Cation exchange capacity
Cu	=	Copper
DAS	=	Days of sampling/composting
DMRT	=	Duncan Multiple Range Test
EC	=	Electrical conductivity
Fe	=	Iron
K	=	Potassium
Mn	=	Manganese
N	=	Nitrogen
P	=	Phosphorus
TN	=	total nitrogen
TOC	=	Total organic carbon
WHC	=	Water holding capacity
WSC	=	Water-soluble carbon
WSCHO	=	Water-soluble carbohydrate
Zn	=	Zinc

Additional information

Notes on contributors

Rajesh Kumar

Rajesh Kumar is an Assistant Professor-cum-Junior Scientist at Bihar Agricultural University, Sabour, India. He has more than 10 years of teaching and research experience specializing in Soil Physics. He has published several research articles/reviews in reputed journals.

Shankar Jha

Shankar Jha is a Soil Scientist at Dr. RPCAU, Pusa, India. He has 15 years of experience in research and specialized in Natural Resource Management. He has published various research articles/reviews/technical reports and authored books in different publications. He has also served as editor/co-editor for different journals and has received prestigious awards at different scientific forums.

Shiveshwar Pratap Singh

Shiveshwar Pratap Singh as Soil Scientist has more than 15 years of research experience in the field of soil fertility, nutrient management, salt-affected soils, waste recycling, and vermicomposting. He has published 35 peer-reviewed research articles in national and international journals and several books.

Mukesh Kumar

Mukesh Kumar is a Professor and Head of the Department of Soil Science at Dr. RPCAU, Pusa, India. He has a vast experience in research, teaching, and extension. He has guided several students in their thesis. He has published several research articles/reviews and authored books fin reputed publications. He has also served as editor/co-editor for different journals and has received prestigious awards at different scientific forums.

Ragini Kumari

Ragini Kumari is an Assistant Professor-cum-Junior Scientist at Bihar Agricultural University, Sabour, India. She has more than 10 years of teaching and research experience specializing in Soil fertility and Chemistry. She has published 20 research articles/reviews in reputed journals.

Rajeev Padbhushan

Rajeev Padbhushan is an Assistant Professor-cum-Junior Scientist at Bihar Agricultural University, Sabour, India. He has more than 10 years of teaching and research experience specializing in Soil Fertility and Chemistry. He has published more than 50 research articles/reviews in peer-reviewed journals. He has also acted as a reviewer for more than 20 International journals.