Millipedes and earthworms: a comparison of their efficiency and the quality of the resulting products

ABSTRACT

Millicomposting (MIL, with millipedes), vermicomposting (VER, with earthworms) and composting without invertebrates (CNT, control) were compared for the first time in a replicated controlled experiment to evaluate their efficiency and the quality of their products. Vegetal waste was degraded in small closed digesters to emulate household-scale composting. Temperature profiles were similar in the three composting types. Ninety-two days were enough to complete composting and obtain well-stabilized products (humus with C/N< 20; pH from 7 to 7.8). The mean final volume loss was about 8% higher in VER than MIL and CNT (P < 0.01) and it stabilized between the 32nd and 67th days (51.4% in VER, 43% MIL and 44% in CNT). Both invertebrates promoted gains in humus Ca content (about 34.5% higher compared to CNT), whereas the highest K and Mg contents were observed in VER humus. pH, P₂O₅, and S contents were also higher in VER humus than in CNT (all P < 0.05). The leachate volumes, electrical conductivity and Na⁺ and PO₄^3– contents were similar (P > 0.05), while pH and contents of K⁺ and NH₄⁺ were higher and NO₃^– was lower in VER than in MIL (all P < 0.01). This resulted in higher maturity degrees in MIL than VER (NH₄⁺/NO₃^–= 0.01 and 0.93, respectively). Although all three composting types were efficient in producing mature high-quality organic fertilizers, this study showed that the addition of invertebrates improved the composting efficiency and the quality of the final products.

GRAPHICAL ABSTRACT

KEYWORDS:

• Millicomposting
• Vermicomposting
• Rhinocricus padbergi
• Eisenia fetida
• Household composting

Acknowledgments

The authors thank the Núcleo de Apoio Técnico ao Ensino, Pesquisa e Extensão of Instituto de Ciências Ambientais, Químicas e Farmacêuticas da Universidade Federal de São Paulo (NATEPE-ICAQF/UNIFESP) for supporting some experimental work.

Disclosure statement

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

Data availability statement

The data that support the findings of this study are available from the corresponding author, Leda LM, upon reasonable request.

Geolocation information

This experiment was carried out at the location: −23.68368, −46.62855.

Additional information

Funding

The author(s) reported there is no funding associated with the work featured in this article.