The use of the sewage sludge in the agriculture, its possibility of use as a fertilizer was assessed. Four fertilizing treatments were applied to ponds stocked with carp fry. The hydro-chemical parameters of the ponds fertilized with sewage sludge were compared to ponds fertilized with mineral fertilizers and those non fertilized. No statistically significant difference was observed (p < 0.05) between the average total phosphorus concentration in ponds fertilized with the sewage sludge (0.29 mg P·dm^–3) and those fertilized with superphosphate (0.30 mg P·dm^–3). No negative influence of used sewage sludge on pond ecosystem was observed, measured in hydro-biological and hydro-chemical parameters. Proximity analyses did not reveal heavy metals accumulation or human pathogenic organisms presence in fish bodies. The use of sewage sludge can be recommended as the on1y source of phosphorus. Additional mineral nitrogen fertilizer is required due to sludge composition.

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