The conversion of solid palm-oil-mill wastes such as empty fruit bunches (EFB) and palm pressed fibers (PPF) into organic fertilizer has been a major challenge to Central Plantations Group (CPG) in Pekanbaru, Riau, Indonesia. The company had invested heavily in imported machinery to speed up the thermophilic composting process, but the high-energy cost in operating the equipment has rendered it idle.
Andrew, the managing director of CPG, learned that Goducate provides technical support to those interested in vermicomposting. His main focus is on how the palm-oil-mill residues can be fed to earthworms as an economically useful alternative to natural composting, which can take up to six months to complete due to the slow rate of decomposition.
Five months ago, Andrew and his partners purchased 1.5 tons of earthworms from some suppliers in Java and stocked them into 20 vermibeds, each measuring 10.5 sq m. To ascertain whether or not the workers were following the best practices in vermicomposting, Andrew invited us to visit the project to learn from us.
We observed that, aside from some red worms, Lumbricus rubellus was the dominant earthworm species in the vermibeds. We recommended the gradual stocking of African Night Crawlers (ANCs), known scientifically as Eudrilus eugeniae, and multiplying them into large populations, because these are considered the most efficient above-soil-surface composting earthworm in the tropics. Lumbricus is a temperate-sourced earthworm and thrives very well in highlands like those in Bandung and the Karo Highlands. Additionally, unlike ANCs, Lumbricus is an efficient composter of animal manure rather than carbon-based residues like palm-oil-mill wastes.
We also explained that the residual nutrient contents from empty fruit bunches and palm pressed fibers are of low percentages. To produce quality vermicast, we suggested the addition of animal manure from cattle, horses, goat, sheep, or native chickens. The dung from commercially-fed chicken broilers is not ideal for earthworms because it contains traces of antibiotics, which can neutralize the bacteria, fungi, protozoa, and other microbes that serve as food for earthworms. The food combination should ideally be 500 kilos of animal manure for every 3,000 kilos of empty fruit bunches and palm pressed fibers.
Some of the other recommendations we shared with Andrew was the relocation of the vermicomposting project to a bigger site and adjacent to CPG’s palm-oil mill to reduce the transportation costs of raw materials. Another piece of advice was to shift from manual to mechanized operations if the company’s long-term goal is to have a daily vermicast output 10 tons.
Finally, we also encouraged CPG to help popularize vermicomposting through seminars and training, in order to help needy Indonesian farmers help themselves.
