A potential bioconversion of empty fruit bunches into organic fertilizer using Eudrilus eugeniae

Vermicomposting is a process to biotransform organic solid wastes into valuable product, namely vermicompost using epigeic earthworms. Vermicomposting technology may provide a low-input basis for sustainable management of organic solid waste. The present study was to investigate the suitability of oil palm empty fruit bunches to be reused as feedstocks of Eudrilus eugeniae for the duration of 12 weeks. Empty fruit bunches were mixed with cow dung in different ratios to produce five different treatments for laboratory screening of solid waste. The growths of E. eugeniae were monitored weekly. All treatments encouraged the growth of E. eugeniae except the treatment with empty fruit bunches alone. The maturity and quality of vermicompost were assessed through carbon-to-nitrogen ratio, calcium, phosphorus, potassium and magnesium. Generally, all treatments showed increases in total contents of calcium (39.38-373.17 %), phosphorus (15.15-390.54 %), potassium (45.55-153.66 %) and magnesium (55.86-370.93 %) but a decrease in carbon-to-nitrogen ratio (11.24-76.24 %) after 12 weeks of vermicomposting process. Besides, parameters such as pH and electrical conductivity were also investigated in this paper. Among all the treatments investigated, empty fruit bunches that were mixed with cow dung in the ratio of 2:1 were biotransformed into the most superior quality vermicompost (carbon-to-nitrogen ratio, 18.53; calcium, 7.76 g/kg; phosphorus, 3.63 g/kg; potassium, 12.81 g/kg; and magnesium, 4.05 g/kg). In conclusion, vermicomposting could be used as an efficient technology to convert empty fruit bunches into nutrient-rich organic fertilizers if the wastes were mixed with cow dung in an appropriate ratio.