Assessment of the suitability of pineapple waste as feedstock for vermicomposting

Declining soil fertility is a challenge to sustainable agricultural production in sub-Saharan Africa. However, large volumes of agricultural waste are generated from pineapples that could be converted into soil conditioners through vermicomposting utilizing earthworms. Several types of agricultural waste have been studied extensively as vermicompost feedstock, but little work exists on pineapple waste. The objective of this study was to investigate the suitability of pineapple waste as feedstock for vermicomposting. We assessed the physicochemical properties of fresh, pre-composted pineapple waste and the resultant vermicompost. We also studied the optimal feeding rate and stocking density of the system. The study revealed that pre-composting reduced the moisture content (29%), volatile organic carbon (VOC) (10%), and increased the pH (57%), which was helpful in waste stabilization as well as in the mass reduction of the waste. Vermicomposting after precomposting increased the bulk density (92%), ash content (25.4%), pH (10%), EC (14%), total phosphorus (21%), and total potassium (28%). The technology also decreased the moisture content (1%), VOC (12%), total organic carbon (81%), total nitrogen (22%), and the carbon to nitrogen ratio (76.4%) of the pineapple waste hence yielding a more stabilized and mineralized vermicompost. The study further revealed an optimal feeding rate of 2 kg feeds/kg worms and a stocking density of 1 kg worms m-2 for total nitrogen and phosphorus mineralization of the pineapple waste. The degradation of the pineapple waste by earthworms demonstrated the practicability of vermicomposting as a low-cost and straightforward technology of converting pineapple waste into a nutrient-rich soil amendment.