Evaluation of effluent from fish (Labeo rohita) scale processing as a fertilizer for paddy (Oryza sativa) production

Purpose Fish scale contains two important constituents, the hydroxyapatite and collagen. The purpose of this paper was to use the dried form of the effluent, called Fish Scale Effluent (FSE), generated through simultaneous recovery of these constituents, as a fertilizer.Method The FSE was obtained from Labio rohita (Rohu) scale by treatment in sequence with potassium hydroxide, phosphoric acid, and ammonium sulfate. Chemical composition of FSE was analyzed. The FSE was applied as a sole fertilizer for IR36 paddy plant grown on sand in plastic pot. Various growth parameters and grain qualities were evaluated.Results FSE contained most of the macro- and micro- elements required for growth, and the plant could be harvested by 126 days. Among different concentrations, 2% FSE (w/v) solution gave the best growth results, viz., plant height at maturity (98 cm), effective tillers (22.2/plant), spikelets (90/panicle), paddy production (44.2 g filled grain/plant) and chaffyness (only 2.85% of total paddy). The paddy thus produced exhibited 75.11% hulling, the de-hulled rice containing 55.18% of whole kernel having hardness of around 6 kg. The brown rice contained (sample basis) protein, fat, fibre, ash, and carbohydrate as 7.40%, 1.71%, 0.93%, 1.11% and 75.35%, respectively; morphology of the starch granule being irregular polyhedral in shape with maximum size lt;10 µm.Conclusion Since these plant growth and grain quality criteria are in acceptable limit, the FSE could be utilized as a potential fertilizer for paddy production.