Aim – To study the comparative toxicity of chemical and organic fertilizers on earthworm, Eisenia fetida. Methodology-Eisenia fetida is an epigeic earthworm species widely used in laboratory eco-toxicological studies. OECD (1984) recommendations no 207 (1984) were used to set up the laboratory experimental conditions. Calculation of lethal concentration (LC50) of Urea and DAP was done through Finney’s Probit analysis. The duration of the test for calculation of LC50 was 14 days. LC50 for urea was 876.56 mg/kg and LC50 for DAP was 2098.69 mg/kg of soil. Experiment was carried out in Control along with four treatment groups T1, T2, T3, T4. In Treatment sets earthworms were exposed to T1 (1/2 LC50 Urea) and T2 (1/2 LC50 DAP) sub lethal doses (mg/kg of artificial soil) of commercially available chemical fertilizers. In Treatment sets T3 and T4 dosage (1000 mg/kg of artificial soil) of organic fertilizer and vermicompost were added. The observations were taken on 1, 15, 30, 45, and 60th day on the predecided parameters. The mean change in weight of worms and cocoon production rate throughout the experimental period was assessed. Result-Significant variation in weight of worms was observed in experimental sets (T1 and T2) with chemical fertilizers. Earthworm weight was more in T2 than T1. The lowest Cocoon production was observed in T1. The highest weight and Cocoon production count were observed in T4 followed by T3. The result indicates the detrimental effect of chemical fertilizers on growth and reproductive parameters of Eisenia fetida. Conclusion The present study findings indicate that usage of chemical fertilizers in agriculture raise serious concern that fertilizers also cause toxicity to earthworm survival. one of the important soil fauna, are vulnerable to two widely used nitrogenous fertilizers, urea and DAP. A sustainable agro-ecosystem will be achieved in the future by encouraging earthworm activity in the soil through the use of sufficient amounts of organic manure in crops rather than chemical fertilizers.

Cocoon, Chemical fertilizers, Earthworm, Organic fertilizers, Weight.