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Human urine (HU) is a biogenic fertilizer which has raised immense interest owing to its capacity of combining sanitation and nutrient recovery. In search of an alternative organic fertilizer for fish culture, the nutrient potential of HU was evaluated. Fries of Indian carps and larvae of freshwater prawn were reared for 120 days under six conditions: (a) aerated and (b) non-aerated fresh HU (0.01%), (c) cattle manure (CM; 1.8 kg tank−1), mixed treatment with CM and HU under (d) iso-phosphorus and (e) iso-nitrogenous condition and (f) control. Monitoring of water quality and biological parameters revealed that total fish yield was the highest in CM (621.5 g tank−1) followed by mixed treatments under iso-nitrogenous (428 g tank−1) and iso-phosphorus (333 g tank−1) conditions, aerated HU (321 g tank−1) and HU (319 g tank−1). The gross primary productivity (GPP) in HU was satisfactory (601.8 mg C m−2 h−1) and superior to all but CM treatment. The abundance of heterotrophic bacteria (HB) was highest in CM and lowest in HU. Both GPP and HB population were correlated positively with fish yield per tank. Although pH in all treatments remained high (pH 8.4–8.9), no ammonia toxicity was observed. No E. coli infestation in any fish muscle was encountered. The concentrations of cadmium and lead in fish muscle were within respective safe level. The study established that high fertilizer potential of HU could be exploited as an alternative organic fertilizer or as a candidate to be blended with cattle manure.
相似文献The study examined the impact of raking and fish bioturbation on modulating phosphorus (P) concentrations in the water and sediment under different trophic conditions. An outdoor experiment was set to monitor physicochemical and microbiological parameters of water and sediment influencing P diagenesis. A pilot study with radioactive 32P was also performed under the agency of raking and bacteria (Bacillus sp.). Raking was more effective in release of P under unfertilized conditions by significantly enhancing orthophosphate (35%) and soluble reactive phosphate (31.8%) over respective controls. Bioturbation increased total and available P in sediments significantly as compared to control. The rates of increase were higher in the unfertilized conditions (17.6–28.4% for total P and 12.2 to 23.2% for available P) than the fertilized ones (6.5–12.4% for total P and 9.1 to 15% for available P). The combined effects of raking and bioturbation on orthophosphate and soluble reactive phosphate were also stronger under unfertilized state (54.5 and 81.8%) than fertilized ones (50 and 70%). The tracer signature showed that coupled action of introduced bacteria and repeated raking resulted in 59.2, 23 and 16% higher counts of radioactive P than the treatments receiving raking once, repeated raking and bacteria inoculation, respectively. Raking alone or in sync with bioturbation exerted pronounced impact on P diagenesis through induction of coupled mineralization and nutrient release. It has significant implication for performing regular raking of fish-farm sediments and manipulation of bottom-grazing fish to regulate mineralization of organic matter and release of obnoxious gases from the system. Further, they synergistically can enhance the buffering capacity against organic overload and help to maintain aquatic ecosystem health.
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