Vermistabilization of Corn Cob Husk and Seed Germination Bioassay of Vigna Unguiculata for Quality Assessment of Vermicompost

Vermistabilization is a process where composting earthworm species are used to convert organic waste materials into humus-like substances called vermicompost. The present study involved two experiments to explore the vermistabilization potential of corn cob husk and quality assessment of vermicompost produced through seed germination bioassay of Vigna unguiculata. The first experiment was arranged as two factor – factorial completely randomized design with three replicates. Factor one was the size of corn cob husk pieces (two levels; < 2 cm and 2-4 cm) while the factor two was the ratio between cow dung (CD) to corn cob husk (CH) pieces (four levels; 75% CD + 25% CH, 50% CD + 50% CH, 25% CD + 75% CH and 100% CH). A simple randomized design was employed for the second experiment to assess the quality of the vermicompost using the aqueous solutions, with deionized water serving as a control. The bio converting agent of the present study was red earthworms (Eisenia fetida). Two-way ANOVA was used to analyze the qualitative data of the first experiment while one-way ANOVA was used in the second experiment. Weight of end-substrate and vermicompost, substrate reduction rate (%), live biomass of earthworms, changes of live biomass of earthworms (%) nitrogen content (N%), pH, electrical conductivity (EC), total dissolved solids (TDS) and salinity of the vermicompost together with the quality parameters of color and odor were recorded at 75 days after establishment of the first experiment.
Relative seed germination (RSG%), relative radicle growth (RRG%) and germination index (GI%) were calculated three days after seed sowing in the second experiment. Results revealed that the interaction effect between two factors significantly affected the live biomass of the earthworms, N%, EC and TDS of the vermicompost. Apart from pH, other parameters measured in the first experiment were influenced either by factor one or two. When looking at the quality aspects, only the color of the vermicompost varied significantly among treatments. According to the results of the germination bioassay, RSG%, RRG% and GI% were significantly different among treatments (P<0.05). Overall, the highest efficacy on and greater quality of the vermicompost were recorded when preparing substrate by mixing with 75% of CD with the particle size of CH < 2 cm. Vermicomposting has thus been shown to be an effective technique for handling CH when mixing with CD. However, converting CH without combining it with CD seems ineffective.