Assessment on suitability of water hyacinth for organic fertilizer production

Abstract

Water hyacinth is a noxious aquatic weed mostly found in nutrient-rich water bodies. They are invasive species, and increasingly becoming a threat to local fishing industries, drainages, irrigation and navigation in many waterways in southwestern Nigeria. This is largely due to rapid urbanization and industrialization of the region over the years, resulting in extensive pollution of the waterways. This study examines the quality of four major waterways (Awba dam, Eleyele river, Epelagoon and Majiduncreek) within the southwestern Nigeria and nutrient contents of their water hyacinth weed compositions for organic fertilizer production. Twenty samples each of water hyacinth, surface water and sediments were collected from the four water bodies’. The physico-chemical properties of surface water, sediment and water hyacinth samples were analyzed along with heavy metals (Pb, Cd, Cr, Co, Cu and Ni). Standard analytical techniques were employed for chemical analysis. The surface water bodies recorded very high levels of organics (72.0±3.87 to 154±8.44 mg/L) and nitrate (7.36±0.17 to 19.4±1.05 mg/L) indicating gross organic pollution. Sediments similarly showed high organic content with values ranging between 4.87±0.53 to 47.0±17.3 %. Water hyacinth from the four surface water bodies showed proportional levels of organic carbon, nitrogen and phosphorous with C/N ratios of 11.2 to 13.1%. The NPK ratios of these water hyacinths were comparable with commercially available fertilizers suggesting their suitable as alternatives. Analysis of variance (0.05) showed no significant differences in quality parameters among the four sample locations of surface water, sediment and water hyacinth. The water hyacinth weeds were rich in nutrients needed by food crops. This potential could be harnessed to transform this aquatic nuisance to organic fertilizer in order to reduce cost of fertilizer, boost food production and create job opportunities. Further research is needed to determine economically suitable methods of converting water hyacinth to commercially available organic fertilizer.