VERMICOMPOSTING OF ORGANIC WASTE AND ITS EFFECT ON GROWTH OF CORHORUS OLITORIUS

Abstract

Improper management of organic waste in Nigeria constitutes one of the major health risks to the public. Vermicomposting, a non-thermophilic biodegration of organic waste using species of earthworms, has been identified as a technique for efficient management of organic wastes, which otherwise could have constituted public health problem. However, not much work has been reported about vermicomposting and its usefulness in Nigeria. This study was therefore designed to assess the use of earthworms to biodegrade organic waste and its effect on the growth of Corchorus olitorius, a vegetable commonly consumed in Southwest Nigeria. Laboratory based experimental design was adopted. Fresh kitchen wastes collected from three Food Canteen within University College Hospital, lbadan were shredded and mixed with cow dung from Bodija abaitoir in a ratio of 2:1. Samples were analysed for physicochemical parameters: Organic Carbon (OC), Nitrogen (N), Phosphorus, and Potassium, using American Public Health Association standards. Six kilogramme of the waste mixture was composted with earthworms of the species Endrilius eugeniae. Temperature (⁰C) and Moisture Content MC (%) were determined, weekly. Vermicompost (VC) was produced and analysed after two months and compared to a known inorganic fertilizer NPK (20-10-10). The effect of VC on the growth of Corchorus olitorius was evaluated on 1kg of soil under greenhouse condition for five weeks. Five treatments (A-E) with three replicates each were used: control (A), VC 2.5t/ha (B). VC 5.0t/ha (C), VC 10t/ha (D), NPK fertilizer 25.0kgN/ha (E). Number of leaves of Corchorus olitorius was counted and height (cm) was measured using tape rule at three, four, and five weeks after planting. Data were analysed using descriptive statistics and ANOVA at p <0.05. The OC, Nitrogen, Phosphorus, Potassium content and Carbon-Nitrogen (C-N) ratio of the wastage mixture before vermicomposting were: 20.2 ± 0.1%, 0.9 ± 0.1%, 0.1 ± 0.0%, 0.3 ± 0.6%, and 23.4 respectively. The mean temperature and MC observed were 25.6 ±8.3°C and 54.1 ± 5.9% respectively. An odourless, granular and homogenous vermicompost of 2.8 kg was obtained. The OC, Nitrogen, Phosphorus, Potassium content and C-N ratio of vermicompost were: 11.3 ± 0.6%. 1.3± 0.0%, 2.0 ± 0.6%, 2.5 ±0.0%, and 8.8 respectively. The mean number of leaves and height (cm) of Corchorus olitorius at five weeks for A, B, C, D, and E were: 10.3 ± 0.6, 11.0 ± 0.0, 11.3 ± 0.6, 12.7 ± 1.2, 12.7 ± 1.2, and 27.3 ± 4.2 cm, 36.1 ± 3.1cm, 34.7 ± 4.5cm, 50.4 ± 4.8cm, 50.1 ± 2.3cm, respectively. There was significant difference in mean number of leaves and height of Corchorus olitorius in all the five treatment. The Nitrogen-Phosphorus-Potassium values of vermicompost obtained when compared to inorganic fertilizer suggest that vermicomposting is an environmentally acceptable technique for the conversion of organic waste, with a potential to reduce human exposure to health risks. Research into vermicomposting on a large scale and its adoption for the management of organic waste in Nigeria is advocated.