Assessing the potential of recycling sugarcane pressmud and bagasse using vermicomposting

Abstract

The sugar processing industry highly contributes to socioeconomic development and livelihood support in Uganda. However, the industry generates huge quantities of wastes including: bagasse, sugarcane pressmud and vinnase which remain underutilized thus posing an environmental pollution risk. On this basis, the study explored the conversion of sugarcane pressmud and bagasse into vermicompost using earthworms. The vermicomposting experiment was set up as follows; Pressmud and bagasse were mixed in three different ratios of 22.5 (kg) PM: 7.5 (kg) BG, 20 (kg) PM: 10 (kg) BG and 15 (kg) PM: 15(kg) BG, to form treatments T2, T3, and T4, respectively. A control treatment (T1) without bagasse (30 kg PM) was also included in this study. Each reactor was seeded with earthworms (Eudrilus eugniea) at a stocking density of 3 kg/m3 (0.4 kg of earthworm biomass) with cow dung as the bedding material. All the treatments were set up in triplicates and operated in batch mode for 60 days. Samples of waste mixtures at the onset of the experiment and vermicomposts after harvest were analyzed for NPK, TOC, Ca, and selected heavy metals. The harvested vermicompost was assessed as soil fertilizer in comparison with inorganic fertilizer (NPK) with spinach (Beta vulgaris cicla) as the study crop at the fertilizer application rate of 90 kgN/ha. Results showed significant differences in, total carbon, nitrogen, potassium, calcium and copper while no significant changes were recorded for pH, C/N, phosphorous, zinc, chromium, lead and cadmium. Spinach performance in terms of height, number of leaves, fresh and dry weight significantly (p<0.05) improved with application of fertilizers over the control without NPK and vermicompost. Combined treatment of organic manure and inorganic fertilizer (D+U) showed superiority in plant growth characters. The least crop performance was observed in the treatment without any fertilizer application (control). Treatments with vermicomposts (S and T) also positively affected spinach growth and yield performance. In conclusion, vermicomposting could be used as a green technology to manage and bio-convert sugarcane pressmud and bagasse into nutrient-rich organic fertilizers.