Millicomposting And Vermicomposting: An Alternate Eco-Friendly Technique for Soil Reclamation and Its Impact on Germination of Raphanus Raphanistrum Subsp. Sativus (L.) Domin on Microplastic Polluted Soil

Abstract

Background:
Soil contamination with biodegradable plastics poses challenges for sustainable agriculture, and the role of macrofaunal decomposers in mitigating these effects remains understudied.
Aim:

To compare earthworm- mediated composting (vermicomposting) and millipede-mediated composting (millicomposting) in bioplastic-polluted soil.

Methodology:
Millicompost and vermicompost were prepared in pots containing 3 kg sieved forest soil and ±20 g biodegradable plastics (<4 cm). Maintained at 60–80% moisture and 25–30°C, soils were inoculated with earthworms (T_E, T_E+P) or millipedes (T_M, T_M+P). After 30 days, pH, electrical conductivity, organic carbon, nitrogen (Kjeldahl), phosphorus (Olsen), and potassium (Toth-Prince) were analyzed. Micronutrients (Fe, Mn, Zn, Cu) were quantified via Atomic Absorption Spectroscopy. Surface-sterilized Raphanus raphanistrum subsp. sativus seeds were sown in treatment soils (Tc, T_E, T_M, T_E+P, T_M+P) in sterile Petri plates. Following 7-day germination under white light, germination percentage was calculated as (germinated/total sown) × 100. Data were analyzed in triplicate (mean ± SE) using one-way ANOVA.

Results:

 Earthworms significantly enhanced N (137%) and P (436%) compared to modest millipede gains. Both macrofauna augmented micronutrients (10–18%) via bioturbation. While bioplastics reduced pH and EC (31%), germination improved from 67% to 87%. Earthworms successfully maintained high nutrient levels (N: 119.0; P: 5.08 kg ha⁻¹) in plastic-amended soils, demonstrating robust bioremediation potential.

Conclusion: These findings highlight invertebrate-mediated composting as an effective bioremediation strategy for enhancing soil fertility and resilience in the face of emerging plastic pollution.